Contents at a Glance
1 Introduction and Development of the PC 2 Pc components, features and Control 3 Basic Electronics 4 SMPS 5 Motherboards and Add-on Cards 6 Processor Types and Specifications 7Memory 8Hard Disk Drive 9Optical Storage 10Input Devices 11 BIOS 12 Video Hardware 13 Printers and Scanners 14 Operating System 15 PC Diagnostics, Testing and Maintenance
Lesson -1
Introduction and Development of the PC
Characteristic and features of computer Pc components, features and Control Components of System and its feature Types of Computer Software Types Operating System
Computer:-
The word computer comes from the word ―compute‖, which means, ―to calculate‖. Computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.
A computer is also called as data processor because it can store, process, and retrieve data whenever requires. The activity of processing data using a computer is called data processing.
―Data‖ is raw material used as input and ―Information‖ is processed data obtained as output of data processing.
Processing: -Manipulation of data in the computer. Manipulation means calculations, comparisons, sorting of data. Characteristic of computers:- 1. Automatic 2. Speed 3. Accuracy 4. Diligence 5. Versatility 6. Power of remembering 7. No I. Q. 8. No feelings
Basic Function of Computer: -
1. Inputting: -Processing of entering of data and instructions into a computer system. 2. Storing: -Saving data and instructions to make them readily for initial or additional processing and when required. 3. Processing: -Performing arithmetic operation (add, subtract, multiply, divide, etc) or logical operations (comparisons like equal to, less than, greater than, etc) on data to convert them to useful information. 4. Outputting: -Process of producing useful information or results for a user, such as printed report or visual display. 5. Controlling: -Directing the manner and sequence in which the above operations are performed.
Hardware: - Hardware is a comprehensive term for all of the physical parts of a computer. Most visible hardware part of a desktop PC consists of: - System Unit (Cabinet) Monitor Keyboard Mouse UPS Printer
Inside the system unit box (Cabinet) the major hardware are: - Motherboard (Includes Chipsets and Daughter cards according to Expansion slots) Processor (CPU or Microprocessor) RAM (Primary Memory) ROM (BIOS chip) SMPS (Power supply) Hard Disk (Secondary Storage) DVD-Drive (Secondary Storage)
Processor or C.P.U.(Central Processing Unit): -The two basic unit component ofC.U. (Control Unit)andA.LU. (Arithmetic and Logic Unit). C.U.: -It acts as a central nervous system for other components of a computer system. It manages and coordinates the entire computer system. A.L.U.: -Performing arithmetic operation (add, subtract, multiply, divide, etc) or logical operations (comparisons like equal to, less than, greater than, etc). MOTHER BOARD: -A Motherboard is the central printed circuit board (PCB) it holds many of the crucial components of the system, like Chipsets, Expansion cards, RAM, ROM, while providing connection for other peripherals. Primary Memory: - It is also known as main memory of computer system. It is used to hold pieces of program instruction and data, intermediate results of processing.Example: -RAM, ROM. Secondary Memory: -It is also known as auxiliary memory. It is used to take care of limitations of primary storage. It supplements the limited storage capacity and the volatile characteristic of primary memory.Example: - Magnetic Tape, Floppy Disk, Hard Disk, Compact Disk, DVD, Pen Drive, Memory Chip etc. Input Device: -An input device is an electromechanical device that accepts data from outside world and translates then into from a computer can interpret. Example: - Keyboard, Point and draw device (Mouse, Trackball, Joystick, Electric Pen, and Touch Screen), Data Scanning Devices (Image Scanner (Flatbed Scanner and Hand Held Scanner), Optical Character Recognition (OCR) device (Optical Mark Reader (OMR), Bar-Code Reader, Magnetic- Ink Character Recognition (MICR), Digitizer, Electronic Card Reader, Speech Recognition Device.
Output Device: -An input device is an electromechanical device that accepts data from computer and translates them into a form suitable for use by users.Example: - Monitors (There are two basic types of monitors 1. CRT (Cathode Ray Tube) 2. Flat Panel (LCD, TFT, PLASMA, LED DISPLAY).Printers (Dot Matrix Printers, Inkjet Printers, Drum Printers, Chain/Band Printers, Laser Printers), Plotters (Drum Plotter, Flatbed Plotter), Screen Image Projector, Voice Response Systems.
Classification of computers: -
Analogue Computer: - Analog computers are used to process continuous data. Analog computers represent variables by physical quantities. Thus any computer which solve problem by translating physical conditions such as flow, temperature, pressure, angular position or voltage into related mechanical or electrical related circuits as an analog for the physical phenomenon being investigated in general it is a computer which uses an analog quantity and produces analog values as output. Thus an analog computer measures continuously. Analog computers are very much speedy. They produce their results very fast. But their results are approximately correct. All the analog computers are special purpose computers. Digital Computer: - Digital computer represents physical quantities with the help of digits or numbers. These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user. Hybrid Computer: - Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system. Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world.
The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form. Type of Digital Computer: - 1. Laptop Computer:-The smallest computer in size has been developed. This type of small computers look like an office brief case and called "LAPTOP" computer. The laptops are also termed as "PORTABLE COMPUTERS." Due to the small size and light weight, they become popular among the computer users. The businessmen found laptop very useful, during traveling and when they are far away from their desktop computers. A typical laptop computer has all the facilities available in microcomputer. The smallest laptops are called "PALMTOP".
2. Micro Computer: -These are the smallest range of computers. They were introduced in the early 70‘s having less storing space and processing speed. Microcomputers of todays are equivalent to the mini computers of yesterday in terms of performing and processing. They are also called ―computer of a chip‖ because its entire circuitry is contained in one tiny chip. The micro computers have a wide range of applications including uses as portable computer that can be plugged into any wall.
3. Mini Computer:-Mini computers are smaller than mainframes, both in size and other facilities such as speed, storage capacity and other services. They are versatile that they can be fitted where ever they are needed. Their speeds are rated between one and fifty million instructions per second (MIPS). They have primary storage in hundred to three hundred megabytes range with direct access storage device.
4. Super Mini Computer: - Super mini computers is a high speed performance compared to ordinary mini computer and also has a large amount of memory compare to mini computers and also most powerful type of mini computers, capabilities more commonly associated with mainframes.
5. Mainframe Computer: - The most expensive, largest and the most quickest or speedy computer are called mainframe computers. These computers are used in large companies, factories, organizations etc. the mainframe computers are the most expensive computers; they cost more than 20 million rupees. In this computers 150 users are able to work on one C.P.U. The mainframes are able to process 1 to 8 bits at a time. They have several hundreds of megabytes of primary storage and operate at a speed measured in Nano second. 6. Super Computer: - Large scientific and research laboratories as well as the government organizations have extra ordinary demand for processing data which required tremendous processing speed, memory and other services which may not be provided with any other category to meet their needs. Therefore very large computers used are called Super Computers. These computers are extremely expensive and the speed is measured in billions of instructions per seconds.
SOFTWARE The term software refers to a set of computer programs, procedures, and associated documents describing the programs and how they are to be used. Program: -A sequence of instructions (command) written in a language understood by a computer is called a computer program.
TYPES OF SOFTWARE: -
1. SYSTEM SOFTWARE 2. APPLICATION SOFTWARE
SYSTEM SOFTWARE: -It is set of one or more programs designed to control the operation and extend the processing capability of computer system.
Types of System Software: - 1. Operating System: -It is an integrated set of programs that controls the resources (CPU, memory, I/O devices, etc) of a computer system and provides its users with interface or virtual machine. 2. Programming Language Translator: -It used to transform the instructions prepared by the programmers in a programming language into a form that computer can understand and execute. 3. Communication Software: -It enables transfer of data and programs from one computer to another. 4. Utility Programs: - It helps in system maintenance tasks, and in performing task of routine nature.
APPLICATION SOFTARE: -
It is a set of one or more programs designed to solve a specific problem, or do a specific task. Some commonly known application software is: 1. Word-Processing Software: -It enables us to make use of computer for creating, editing, viewing, formatting, storing, retrieving, and printing the documents. 2. Spreadsheet Software: -It is a numeric-data-analysis tool that allows us to create a kind of computerized ledger. 3. Database Software: -It enables us to create a database, maintain it, organize it data in desired fashion. 4. Graphics Software: -It enables us to use a computer system for creating, editing, viewing, sorting, retrieving, and printing designs, drawing pictures, graphs, etc. 5. Personal Assistance Software: -It allows us to use personal computers for storage and retrieval of our personal information as well as planning and managementof our important items. 6. Education Software: -It allows a computer to use as teaching and learning tool. 7. Entertainment Software: -It allows a computer to use as an entertainment tool. OPERATING SYSTEM: -
Main function of Operating System: -
1. Process Management: -This module takes care of creation and deletion of process, scheduling of system resources to different processes requesting them, and providing mechanisms for synchronization and communication among processes. 2. Memory Management: -This module take care allocation and de-allocation of memory space to programs in need of this resource. 3. File Management: -This module takes care of file-related activities such as organization, storage, retrieval, naming, sharing, and protection of file. 4. Security: -This module protects the resources and information of a computer system against destruction and unauthorized access. 5. Command Interpretation: -This module takes care of interpreting user command, and directing system resources to process the command.
TYPES OF OPERATING SYSTEM: -
1. Single User Multi Tasking: -Single-user operating system is usable by a single user at a time, but it enables user to work with multiple task at the same time. 2. Multi User Multi Tasking / Multiprogramming: -The operating systems of this type allow a multiple users to access a computer system concurrently. Multi-user systems as they enable a multiple user access to a computer through the sharing of time. 3. Distributed Operating System: -An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each other, gave rise to distributed computing. 4. Embedded Operating System: -The operating systems designed for being used in embedded computer systems are known as embedded operating systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE, FreeBSD and Minix 3 are some examples of embedded operating systems. 5. Real Time: -A real-time operating system (RTOS) is a multitasking operating system intended for applications with fixed deadlines (real-time computing). Such applications include automobile engine controllers, industrial robots, spacecraft, industrial control, and some large-scale computing systems.
List of Popular Operating system: -
Unix Linux Ubuntu Kubuntu Fedora
Mac OS X FreeBSD Solaris RHEL Centos HP-UX Linux mint IBM OS/2 Warp SuSE Linux MS-DOS
Window 95 Window 98 Window 98 SE Window 2000 Window XP
XP sp-1,sp-2,sp-3 Window Vista Window 7 Window 8 Window 2000 server
Window 2008 Window 2012 Window 2003 server server server
Lesson -3
Basic Electronics
Types of Electronics Component Resistor Capacitor Inductor Semi-Conductor Diode Transistor I.C.
Tools Required for Electronics
Soldering Iron: -
For electronics work the best type is one powered by mains electricity (230V in the UK), it should have a heatproof cable for safety. The iron's power rating should be 15 to 25W and it should be fitted with a small bit of 2 to 3mm diameter.
Other types of soldering Iron
Low voltage soldering iron are available, but their extra safety is undetermined if you have a mains lead to their power supply! Temperature controlled irons are excellent for frequent use, but not worth the extra expense if you are beginner. Gas-powered irons are designed for the use where no mains supply is available and are not suitable for everyday use. Pistol shaped solder guns are far too powerful and cumbersome for normal electronics use.
Soldering iron stand
You must have a safe place to put the iron when you are not holding it. The stand should include a sponge which can be dampened for cleaning the tip of the iron.
Desoldering pump (solder sucker)
A tool for removing solder when de-soldering a joint to correct a mistake or replace a component.
Solder remover wick (copper braid) This is an alternative to the desoldering pump.
Reel of solder The best size for electronics is 22swg (swg = standard wire gauge).
Solder is an alloy, which is a combination of two or more metals. The most common solder is called half-and-half, or "plumber's" solder, and is composed of equal parts of lead and tin. Other metals used in solder are aluminum, cadmium, zinc, nickel, gold, silver, palladium, bismuth, copper, and antimony.
Side cutters For trimming component leads close to the circuit board.
Wire strippers
Most designs include a cutter as well, but they are not suitable for trimming component leads.
Small pliers Usually called ‗spine nose‘ pliers, these are for bending component leads etc. If you put a strong rubber band across the handles the pliers make a convenient holder for parts such as switches while you solder the contacts.
Multipurpose screwdriver set
For scraping away excess flux and dirt between tracks, as well as driving screws various component such as smps, motherboard, cabinet and laptop.
Heat sink You can buy a special tool, but a standard crocodile clip works just as well and is cheaper.
Track cutter
A 3mm drill bit can be used instead, in fact the tool is usually just a 3mm drill bit with a proper handle fitted.
Multimeters
Multimeter's are very useful test instruments. By operating a multi-position switch on the meter they can be quickly and easily set to be a voltmeter, an ammeter or an ohmmeter. They have several settings (called 'ranges') for each type of meter and the choice of AC or DC. Some multimeter's have additional features such as transistor testing and ranges for measuring capacitance and frequency.
Choosing a multimeter
A digital multimeter is the best choice for your first multimeter, even the cheapest will be suitable for testing simple projects. If you are buying an analogue multimeter make sure it has a high sensitivity of 20k /V or greater on DC voltage ranges, anything less is not suitable for electronics. The sensitivity is normally marked in a corner of the scale, ignore the lower AC value (sensitivity on AC ranges is less important), the higher DC value is the critical one. Beware of cheap analogue multimeter's sold for electrical work on cars because their sensitivity is likely to be too low.
Digital multimeter's
All digital meters contain a battery to power the display so they use virtually no power from the circuit under test. This means that on their DC voltage ranges they have a very high resistance (usually called input impedance) of 1M or more, usually 10M , and they are very unlikely to affect the circuit under test.
Digital meters have a special diode test setting because their resistance ranges cannot be used to test diodes and other semiconductors.
Typical ranges for digital multimeter's like the one illustrated: (the values given are the maximum reading on each range).
DC Voltage: 200mV, 2000mV, 20V, 200V, 600V.
AC Voltage: 200V, 600V.
DC Current: 200µA, 2000µA, 20mA, 200mA, 10A*. The 10A range is usually unfused and connected via a special socket.
AC Current: None. (You are unlikely to need to measure this).
Resistance: 200 , 2000 , 20k , 200k , 2000k , Diode Test.
Analogue multimeter's
Analogue meters take a little power from the circuit under test to operate their pointer. They must have a high sensitivity of at least 20k /V or they may upset the circuit under test and give an incorrect reading. See the section below on sensitivity for more details.
Batteries inside the meter provide power for the resistance ranges, they will last several years but you should avoid leaving the meter set to a resistance range in case the leads touch accidentally and run the battery flat.
Typical ranges for analogue multimeter's like the one illustrated: (the voltage and current values given are the maximum reading on each range)
DC Voltage: 0.5V, 2.5V, 10V, 50V, 250V, 1000V.
AC Voltage: 10V, 50V, 250V, 1000V.
DC Current: 50µA, 2.5mA, 25mA, 250mA. A high current range is often missing from this type of meter.
AC Current: None. (You are unlikely to need to measure this).
Resistance: 20 , 200 , 2k , 20k , 200k . These resistance values are in the middle of the scale for each range. It is a good idea to leave an analogue multimeter set to a DC voltage range such as 10V when not in use. It is less likely to be damaged by careless use on this range, and there is a good chance that it will be the range you need to use next anyway!
Electronics is the branch of science that deals with the study of flow and control of electrons (electricity) and the study of their behavior and effects in vacuums, gases, and semiconductors, and with devices using such electrons. This control of electrons is accomplished by devices that resist, carry, select, steer, switch, store, manipulate, and exploit the electron.
There are two types of Basic Electronic components:-
1. Passive(exp:- Resistor, Capacitor, Inductor) 2. Active(exp:- Diode, Transistor, I.C.)
Passive: -Capable of operating without an external power source. Typical passive components are resistors, capacitors, inductors and diodes (although the latter are a special case).
Active: -Requiring a source of power to operate. Includes transistors (all types), integrated circuits (all types), TRIACs, SCRs, LEDs, etc.
DC: -Direct Current. The electrons flow in one direction only. Current flow is from negative to positive, although it is often more convenient to think of it as from positive to negative. This is sometimes referred to as "conventional" current as opposed to electron flow.
AC: -Alternating Current. The electrons flow in both directions in a cyclic manner - first one way, then the other. The rate of change of direction determines the frequency, measured in Hertz (cycles per second).
Frequency:- Unit is Hertz, Symbol is Hz, old symbol was cps (cycles per second). A complete cycle is completed when the AC signal has gone from zero volts to one extreme, back through zero volts to the opposite extreme, and returned to zero. The accepted audio range is from 20Hz to 20,000Hz. The number of times the signal completes a complete cycle in one second is the frequency.
Voltage: -Unit is Volts, Symbol is V or U, old symbol was E . Voltage is the "pressure" of electricity, or "electromotive force" (hence the old term E). A 9V battery has a voltage of 9V DC, and may be positive or negative depending on the terminal that is used as the reference. The mains has a voltage of 220, 240 or 110V depending where you live - this is AC, and alternates between positive and negative values. Voltage is also commonly measured in milli volts (mV), and 1,000 mV is 1V. Microvolts (uV) and nanovolts (nV) are also used.
Current: -Unit is Amperes (Amps), Symbol is I . Current is the flow of electricity (electrons). No current flows between the terminals of a battery or other voltage supply unless a load is connected. The magnitude of the current is determined by the available voltage, and the resistance (or impedance) of the load and the power source. Current can be AC or DC, positive or negative, depending upon the reference. For electronics, current may also be measured in mA (milliamps) - 1,000 mA is 1A. Nanoamps (nA) are also used in some cases.
Resistor: - The object which create the obstruction in the path of current i.e. called resistor.
Resistance: -Unit is Ohms, Symbol is R or Ω. Resistance is a measure of how easily (or with what difficulty) electrons will flow through the device. Copper wire has a very low resistance, so a small voltage will allow a large current to flow. Likewise, the plastic insulation has a very high resistance, and prevents current from flowing from one wire to those adjacent. Resistors have a defined resistance, so the current can be calculated for any voltage. Resistance in passive devices is always positive (i.e. > 0)
Dependency of Resistor:- Length of conductor Cross sectional area of conductor Temperature
Resistor Values – The resistor colour code
Resistor shorthand Resistor values are often written on circuit diagrams using a code system which avoids using a decimal point because it is easy to miss the small dot. Instead the letters R, K and M are used in place of the decimal point. To read the code: Replace the letter with a decimal point, then multiply the value by 1000 if the letter was K, or 1000000 if the letter was M. The letter R means multiply by 1. For Example 560R Means 560Ω 2K7 Means 2.7KΩ = 27000Ω 39K Means 39KΩ 1M0 Means 1.0MΩ = 1000KΩ
The Electronic Industries Association (EIA), and other authorities, specifies standard values for resistors, sometimes referred to as the "preferred value" system. The preferred value system has its origins in the early years of the last century at a time when most resistors were carbon-graphite with relatively poor manufacturing tolerances. The rationale is simple - select values for components based on the tolerances with which they are able to be manufactured.
The EIA "E" series specify the preferred values for various tolerances. The number following the "E" specifies the number of logarithmic steps per decade. The values in any decade can be derived by merely dividing or multiplying the table entries by powers of 10. The series are as follows:
E3 50% tolerance (no longer used) E6 20% tolerance (now seldom used) E12 10% tolerance E24 5% tolerance E48 2% tolerance E96 1% tolerance E192 0.5, 0.25, 0.1% and higher tolerances
While the "E" preferred value lists are the best way to insure one is stocking the optimum number of values for a given tolerance, a word of caution is in order with respect to what is actually available in the marketplace and certain real world practices.
Power Rating of Resistor
The power rating of a resistor is the specification given with a resistor that serves to tell the maximum amount of power that the resistor can withstand. Thus, if a resistor has a power rating of 1/4 watts, 1/4 watts is the maximum amount of power that should be fed into the resistor.
When current passes through electrical components, it normally generates heat. If the current is small enough and suitable for the circuit, this heat is usually negligible and unnoticed in a circuit. But if the current is large enough, it can create a substantial amount of heat in a circuit. The current can melt components and possibly create shorts in a circuit. This is why resistors are given power ratings— to specify the maximum allowable amount of power that can pass through it. If this wattage of power is exceeded, the resistor may not be able to withstand the power and may melt and can create a short in a circuit, which can lead to even greater hazards for the circuit.
The common standard power ratings of resistors are 0.25W, 0.5W, 1W, 2W, 5W, and 25W. So the circuit designer must choose accordingly for the circuit.
The power, P developed in a resistor is given by:
P = I2 × R Where P = Power developed in the resistor in watts (W) Or I = Current through the resistor in amps (A) P = V2 / R R = Resistance of the resistor in ohms (Ω) V = Voltage across the resistor in volts (V)
Various Type of Fixed Resistor:- 1. Carbon Composition Resistor: -Carbon Composition resistor are made of a mixture of powdered carbon and resin binder, and are pressed to form a rod. The resistor is then coated with epoxy. It is oldest type of resistor, but still in used in some appliance.
2. Carbon Film Resistors: -A resistor made of a film of carbon deposited on a substrate. Cuts are made in the film to allow generation of different resistance values. A spiral is used to increase the length and decrease the width of the film, which increases the resistance. Varying shapes, coupled with the resistivity of carbon, (ranging from 9 to 40 µΩm) can make for a variety of resistances.
3. Metal Film Resistors: -A film of low ‗tempco‘ metal alloy (Ni, Cr, Au, Al) or of the metal oxide is deposited on ceramic body, then metal caps are added; a helical groove is cut to trim the value (spiraling), then the body is lacquered and marked.
4. Wire Wounded Resistor: -Resistor wire is wounded on ceramic rod or a glass core. Metal caps are pressed over the end of the rod. The resistor is coated with cement or enamel (high power resistors).
5. Chip Resistor: -Chip resistor surface mount components (SMC or SMD) and are made in either thick- film or thin-film. In thick-film technology, a paste with metal oxide is screen-printed on a ceramic body, dried then fired (this technology is also designated ‗cermet‘). The composition of the metal oxides determines the approximate value of the resistor. Metallic end terminals are attached. The resistor is then laser trimmed to the final value and coated. Thin-film resistors are made by sputtering (a method of vacuum deposition) the resistive material onto an insulating substrate, and then a pattern is etched into the metal layer.
Resistor Networks: - Resistor networks can be discrete components in a single package, but typically are thick or thin film networks. Most leaded networks are in Dual In-Line package (DIP) or single In-Line Package (SIP). Resistor Networks are used to replace sets of chip resistors in large- volume produced electronic products. Handling and mounting components on a PCB is often more expensive than the components themselves.
Variable Resistor Variable resistor consists of a resistance track with connections at both ends and a wiper which moves along the tracks as you turn the spindle. The track may be made from carbon, cermets (ceramic and metal mixture) or a coil of wire (for low resistances). The track is usually called sliders, are also available. The resistance and type of track are marked on the body: 4K7 LIN means 4.7KΩ linear track. 1M LOG means 1MΩ logarithmic track. Some variable resistors are designed to be mounted directly on the circuit board, but most are for mounting though a hole drilled in the case containing the circuit with standard wire connecting their terminals connecting their terminals to the circuit board.
Linear (LIN) and Logarithmic (LOG) tracks Linear (LIN) track means that the resistance changes at a constant rate as you move the wiper. This is the standard arrangement and you should assume this type is required if project does not specify the type of track. Presets always have linear tracks.
Logarithmic (LOG) track means that the resistance changes slowly at one end of the track and rapidly at the other end, so halfway along the track is not half the total resistance! This arrangement is used for volume (loudness) controls because the human ear has a logarithmic response to loudness so fine control (slow change) is required at low volumes and coarse control (rapid change) at high volumes. It is important to connect the ends of the track the correct way round, if you find that turning spindle increases the volume rapidly followed by little further change you should swap the connections to the ends of the tracks.
Application of Variable Resistors There are mainly three types of variable resistors. Potentiometer Variable resistors used as potentiometer have all three terminals connected. This arrangement is normally used to vary voltage, for example to set the switching point of a circuit with a sensor, or control the volume (loudness) in an
Amplifier circuit. If the terminals at the ends of the tracks are connected across the power supply the n the wiper terminal will provide a voltage which can be varied from zero up to the maximum of the supply.
Rheostat This is the simplest way of using a variable resistor. Two terminals are used: one connected to an end of the track, the other to the moveable wiper. Turning the spindle change the resistance between the two terminals from zero up to the maximum resistance.Rheostats are often used to vary current, for example to control the brightness of a lamp or the rate at which a capacitor charges. If the rheostat is mounted on a printed circuit board you may find that all three terminals are connected! However, one of them will be linked to the wiper terminal. This improves the mechanical strength of the mounting but it serves no function electrically.
Presets
These are miniature version of the standard variable resistor. They are designed to be mounted directly onto the circuit board and adjusted only when the circuit is built. For example, to set the frequency of an alarm tone or the sensitivity of a light-sensitive circuit. A small screwdriver or similar tool is required to adjust presets. Presets are much cheaper than standard variable resistors so they are sometimes used in projects where a standard variable resistor would normally be used.
Multi turn presets are used where very precise adjustment must be made. The screw must be turned many times (10+) to move the slider from end of the track to the other, giving very fine control.
Preset (Open Style) Multi Turn Preset Presets (Closed Style)
Light Dependent Resistor (LDR) An LDR is an input transducer (sensor) which converts brightness (light) to resistance. It is made from cadmium supplied (CdS) and the resistance decreases as the brightness of light falling on the LDR increases. A multimeter can be used to find the resistance in darkness and bright light; these are the typical results for a standard LDR: Darkness: maximum resistance, about 1MΩ . Very bright light: minimum resistance, about 100Ω.
For many years the standard LDR has been the ORP12, now the NORPS12, which is about 13mm diameter. Miniature LDR's are also available and their diameter is about 5mm. An LDR may be connected either way round and no special precautions are required when soldering.
Thermistor
A thermistor is an input transducer (sensor) which converts temperature (heat) to resistance. Almost all thermistor's have a negative temperature coefficient (NTC) which means their resistance decreases as their temperature increases. It is possible to make thermistor's with a positive temperature coefficient (resistance increases as temperature increases) but these are rarely used. Always assume NTC if no information is given.
A multimeter can be used to find the resistance at various temperatures; these are some typical readings for example:
Icy water 0°C: high resistance, about 12k . Room temperature 25°C: medium resistance, about 5k . Boiling water 100°C: low resistance, about 400
Suppliers usually specify thermistor's by their resistance at 25°C (room temperature). Thermistor's take several seconds to respond to a sudden temperature change, small thermistor's respond more rapidly.
A thermistor may be connected either way round and no special precautions are required when soldering. If it is going to be immersed in water the thermistor and its connections should be insulated because water is a weak conductor; for example they could be coated with polyurethane varnish.
Resistor combination: - 1. Series Combination. 2. Parallel Combination
Capacitor:-
Function
Capacitors store electric charge. They are used with resistors in timing circuits because it takes time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals.
Capacitance: -
This is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes are used to show the smaller values.
Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):
µ means 10-6 (millionth), so 1000000µF = 1F n means 10-9 (thousand-millionth), so 1000nF = 1µF p means 10-12 (million-millionth), so 1000pF = 1nF
Capacitor values can be very difficult to find because there are many types of capacitor with different labeling systems! There are many types of capacitor but they can be split into two groups, polarised and unpolarised. Each group has its own circuit symbol.
Polarised capacitors (large values, 1µF +)
Electrolytic Capacitors
Electrolytic capacitors are polarised and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering. There are two designs of electrolytic capacitors; axial where the leads are attached to each end (220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board.
It is easy to find the value of electrolytic capacitors because they are clearly printed with their capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it should always be checked when selecting an electrolytic capacitor. It the project parts list does not specify a voltage, choose a capacitor with a rating which is greater than the project's power supply voltage. 25V is a sensible minimum for most battery circuits.
Unpolarised capacitors (small values, up to 1µF)
Small value capacitors are unpolarised and may be connected either way round. They are not damaged by heat when soldering, except for one unusual type (polystyrene). They have high voltage ratings of at least 50V, usually 250V or so. It can be difficult to find the values of these small capacitors because there are many types of them and several different labeling systems!
Many small value capacitors have their value printed but without a multiplier, so you need to use experience to work out what the multiplier should be!
For example 0.1 means 0.1µF = 100nF.
Sometimes the multiplier is used in place of the decimal point: For example: 4n7 means 4.7nF.
Capacitor Number Code
The 1st number is the 1st digit.
The 2nd number is the 2nd digit.
The 3rd number is the number of zeros to give the capacitance in pF.
Ignore any letters - they just indicate tolerance and voltage rating.
For example: 102 means 1000pF = 1nF (not 102pF!)
For example: 472J means 4700pF = 4.7nF (J means 5% tolerance) Capacitor Colour Code
A colour code was used on polyester capacitors for many years. It is now obsolete, but of course there are many still around. The colours should be read like the resistor code, the top three colour bands giving the value in pF. Ignore the 4th band (tolerance) and 5th band (voltage rating).
For example: Brown, black, orange means 10000pF = 10nF = 0.01µ
Note that there are no gaps between the colour bands, so 2 identical bands actually appear as a wide band.
For example:
wide red, yellow means 220nF = 0.22µF.
Polystyrene Capacitors
This type is rarely used now. Their value (in pF) is normally printed without units. Polystyrene capacitors can be damaged by heat when soldering (it melts the polystyrene!) so you should use a heat sink (such as a crocodile clip). Clip the heat sink to the lead between the capacitor and the joint.
Variable Capacitors Variable capacitors are mostly used in radio tuning circuits and they are sometimes called ‗tuning capacitors‘. They have very small capacitance values, typically between 100pF and 500pF (100pF = 0.0001µF). The types illustrated usually have trimmers built in (for making small adjustments) as well as the main variable capacitor. Many variable capacitors have very short spindles which are not suitable for the standard knobs used for variable resistors and rotary switches. It would be wise to check that a suitable knob is available before ordering a variable capacitor. Variable capacitors are not normally used in timing circuits because their capacitance is too small to be practical and the range of values available is very limited. Instead timing circuits uses a fixed capacitor and variable resistor if it is necessary to vary the time period.
Trimmer Capacitors Trimmer capacitors (trimmers) are miniature variable capacitors. They are designed to be mounted directly onto the circuit board and adjusted only when the circuit is built. A small screwdriver or similar too is required to adjust trimmers. The process of adjusting them requires patience because the presence of your hand and the tool will slightly change the capacitance of the circuit in the region of the trimmer! Trimmer capacitors are only available with very small capacitance, normally less than 100pF. It is impossible to reduce their capacitance to zero, so they are usually trimmer capacitor specified by their minimum and maximum values, for example 2-10pF. Trimmers are the capacitor equivalent of presets which are miniature variable resistors.
Tolerance in case of capacitor:- F = +/- 1 % G = +/- 2 % H = +/- 3 % J = +/- 5% K = +/- 10% M = +/- 20 % N = +/- 30 % P = +/- 100 %
Capacitor Combination: -
1. Series Combination 2. Parallel Combination
Inductor: -
An inductor is a coil of wire which may have a core of air, iron or ferrite (a brittle material made from iron). Its electrical property is called inductance and the unit for this is the Henry, symbol H. 1H is very large so mH and µH are used, 1000 µH = 1mh and 1000mH = 1H. Iron and ferrite cores increase the inductance. Inductors are mainly used in tuned circuits and to block high frequency AC signals (they are sometimes called chokes). They pass DC easily, but blocks AC signals this is the opposite of capacitors. Inductors are rarely found in simple projects, but one exception is the tuning coil of a radio receiver. This is an inductor which you may have to make yourself by neatly winding enamelled copper wire around a ferrite rod. Enamelled copper wire has very thin insulation, allowing the turns of the coil to be closed together, but this makes it impossible to strip in the usual way – the best method is to gently pull the ends of the wire through folded emery paper.
Warning: a ferrite rod is brittle so treat it like glass, not iron! An inductor may be connected either way round and no special precautions are required when soldering.
An inductor is used as the energy storage device in some switched-mode power supplies. The inductor is energized for a specific fraction of the regulator's switching frequency, and de-energized for the remainder of the cycle. This energy transfer ratio determines the input-voltage to output-voltage ratio. It is also use for filtration.
Application of Inductor: - Filters Transformers Electromagnets Loudspeaker crossover Networks Automotive Ignitions coils Induction Motors
Diodes
Physical Appearance Circuit Symbol
Function
Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.
Forward Voltage Drop Electricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current- voltage graph).
Reverse voltage When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few µA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown.
Ordinary diodes can be split into two types: Signal diodes which pass small currents of 100mA or less and Rectifier diodes which can pass large currents. In addition there are LEDs (which have their own page) and Zener diode.
Connecting and soldering Diodes must be connected the correct way round, the diagram may be labeled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The cathode is marked by a line painted on the body. Diodes are labeled with their code in small print; you may need a magnifying glass to read this on small signal diodes!
Small signal diodes can be damaged by heat when soldering, but the risk is small unless you are using a germanium diode (codes beginning OA...) in which case you should use a heat sink clipped to the lead between the joint and the diode body. A standard crocodile clip can be used as a heat sink. Rectifier diodes are quite robust and no special precautions are needed for soldering them. Testing diodes
You can use a multimeter or a simple tester (battery, resistor and LED) to check that a diode conducts in one direction but not the other. A lamp may be used to test a rectifier diode, but do NOT use a lamp to test a signal diode because the large current passed by the lamp will destroy the diode.
Signal diodes (low current)
Signal diodes are used to process information (electrical signals) in circuits, so they are only required to pass small currents of up to 100mA. General purpose signal diodes such as the 1N4148 are made from silicon and have a forward voltage drop of 0.7V.
Germanium diodes such as the OA90 have a lower forward voltage drop of 0.2V and this makes them suitable to use in radio circuits as detectors which extract the audio signal from the weak radio signal.
For general use, where the size of the forward voltage drop is less important, silicon diodes are better because they are less easily damaged by heat when soldering, they have a lower resistance when conducting, and they have very low leakage currents when a reverse voltage is applied. Protection diodes for relays
Signal diodes are also used with relays to protect transistors and integrated circuits from the brief high voltage produced when the relay coil is switched off. The diagram shows how a protection diode is connected across the relay coil, note that the diode is connected 'backwards' so that it will normally NOT conduct.
Conduction only occurs when the relay coil is switched off, at this moment current tries to continue flowing through the coil and it is harmlessly diverted through the diode. Without the diode no current could flow and the coil would produce a damaging high voltage 'spike' in its attempt to keep the current flowing.
Rectifier diodes (high current)
Rectifier diodes are used in power supplies to convert alternating Diode Maximum Maximum current (AC) to direct current (DC), a process called rectification. Current Reverse They are also used elsewhere in circuits where a large current must Voltage pass through the diode. 1N40051 1A 50V All rectifier diodes are made from silicon and therefore have a forward voltage drop of 0.7V. The table shows maximum current and 1N4002 1A 100V maximum reverse voltage for some popular rectifier diodes. The 1N4007 1A 1000V 1N4001 is suitable for most low voltage circuits with a current of less than 1A. 1N5401 3A 100V
1N5408 3A 1000V
Bridge rectifiers
There are several ways of connecting diodes to make a rectifier to convert AC to DC. The bridge rectifier is one of them and it is available in special packages containing the four diodes required. Bridge rectifiers are rated by their maximum current and maximum reverse voltage. They have four leads or terminals: the two DC outputs are labeled + and -, the two AC inputs are labeled.
Various types of Bridge Rectifiers
Zener diodes
Zener diodes are used to maintain a fixed voltage. They are designed to 'breakdown' in a reliable and non-destructive way so that they can be used in reverse to maintain a fixed voltage across their terminals. The diagram shows how they are connected, with a resistor in series to limit the current.
Zener diodes can be distinguished from ordinary diodes by their code and breakdown voltage which are printed on them. Zener diode codes begin BZX... or BZY... Their breakdown voltage is printed with V in place of a decimal point, so 4V7 means 4.7V for example.
Zener diodes are rated by their breakdown voltage and maximum power. The minimum voltage available is 2.7V. Power ratings of 400mW and 1.3W are common.
LED
LED's emit light when an electric current passes through them.LED's must be connected the correct way round, the diagram may be labeled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The cathode is the short lead and there may be a slight flat on the body of round LED's If you can see inside the LED the cathode is the larger electrode (but this is not an official identification method).
LED's can be damaged by heat when soldering, but the risk is small unless you are very slow. No special precautions are needed for soldering most LED's.
Never connect an LED directly to a battery or power supply! It will be destroyed almost instantly because too much current will pass through and burn it out.
LED's must have a resistor in series to limit the current to a safe value, for quick testing purposes a 1kΩ resistor is suitable for most LED's if your supply voltage is 12V or less. Remember to connect the LED the correct way round!
Tri-colour LED's
The most popular type of tri-colour LED has a red and a green LED combined in one package with three leads. They are called tri-colour because mixed red and green light appears to be yellow and this is produced when both the red and green LED's are on.
Transistors
Function
Transistors are active components and are found everywhere in electronic circuits. They are used as amplifiers and switching devices.Transistors amplify current, for example they can be used to amplify the small output current from a logic chip so that it can operate a lamp, relay or other high current device. In many circuits a resistor is used to convert the changing current to a changing voltage, so the transistor is being used to amplify voltage.
A transistor may also be used as a switch (either fully on with maximum current, or fully off with no current) and as an amplifier (always partly on). The amount of current amplification is called the current gain, symbol hFE.
Transistors are manufactured in different shapes but they have three leads (legs).
The BASE - This is the lead responsible for activating the transistor.
The COLLECTOR - This is the positive lead.
The EMITTER - This is the negative lead.
Types of transistor
The two main types of transistors are the bipolar junction transistor (BJT) and the field-effect transistor (FET).
Bipolar Junction Transistors
BJTs can have two different polarities, NPN and PNP. An NPN BJT is one where a positively-doped (P-type) semiconductor is sandwiched between two negatively-doped (N-type) semiconductors. A PNP BJT is, obviously, one where an N-type semiconductor is sandwiched between two P-types.
Some specific types of BJTs
HBT – Heterojunction bipolar transistor - These types of transistors are very similar to BJTs except that the two P-type semiconductors in the PNP polarity, or the two N-type semiconductors in the NPN polarity, are doped differently relative to each other. The reason for doing this, simply stated, is to make it more difficult for a transistor to operate in the reverse direction from which is was intended.
Grown-junction transistor - This was the first type of BJT and is self-explanatory. The PN or NP junctions, depending on whether it's of NPN or PNP polarity, respectively, are grown onto a single, solid crystal of semiconductor material. Grown, in this case, means slowly attached, chemically.
Alloy-junction transistor - Similar to a grown-junction transistor except the semiconducting material onto which the PN or NP junctions are grown is specifically germanium.
MAT - micro-alloy transistor - An improved, speedier version of the alloy-junction transistor. The materials of the PN or NP junctions of a MAT are metal-semiconductor, as opposed to semiconductor-semiconductor.
MADT - micro-alloy diffused transistor - An improved, speedier version of the MAT. The dopant material of a MADT is diffused (thinly spread) across the entire germanium crystal prior to PN or NP growth, as opposed to a MAT where the doping material is only on the metallic side of the PN or NP junction.
PADT - post-alloy diffused transistor - An improved, speedier version of the MADT. A thin, diffused dopant layer of germanium is grown onto the germanium crystal, as opposed to the entire germaniumcrystal being diffused, which allows the germanium crystal to be as thick as necessary for mechanical strength purposes. The PN or NP junctions are then grown onto this thin layer.
Schottky transistor - These are alloy-junction transistors with a Schottky barrier between the metal-semiconductor junctions. All metal-semiconductor junctions act sort of like capacitors with a voltage between the junctions. Often, you'd like to minimize this voltage in order to minimize the saturation (the amount of the germanium crystal) needed for the transistor to work. Minimizing the saturation effectively speeds up the transistor's performance, which is great for things like switches. Schottky barriers use various materials to do exactly this.
Surface-barrier transistor - These are just like Schottky transistors except that both junctions are metal- semiconductor as opposed to only one.
Drift-field transistor - The doping agent of these transistors is engineered to produce a specific electric field. This effectually reduces the electrons' transit time between the junctions of the transistor, thereby making it work faster.
Avalanche transistor - These transistors can operate in the breakdown voltage region of a transistor's junctions. The breakdown voltage is simply the minimum voltage in which an insulator starts acting like a conductor. Thus, these transistors allow for higher currents to be applied to them than their normal counterparts.
Darlington transistor - These are simply two BJTs connected together to further increase the gain of the current output.
IGBT - insulated-gate bipolar transistor - These transistors combine the use of BJTs as switches with an isolated-gate FET (see below) as the input. IGBTs provide much more efficient and faster switching than regular BJTs and are thus some of the most common transistors found in modern appliances. \ Photo transistor - These transistors convert electromagnetic radiation in the form of visible light, UV-rays, or X- rays into current or voltage. As opposed to the normal PN junctions found in many transistors, photo transistors use PIN junctions. PIN junctions are similar to PN junctions except that they have an additional intrinsic semiconductor between the P-type and N-type semiconducting regions.
A Darlington pair is two transistors connected together to give a very high current gain. In addition to standard (bipolar junction) transistors, there are field-effect transistors which are usually referred to as FET's. They have different circuit symbols and properties.
Field-Effect Transistors FETs use electric fields to control only one-type of charge carrier, as opposed to BJTs which control both types. FETs are designed to control eitherpositive or negative charge carriers, in the form of holes or electrons, but not both. The flow of positive or negative charge carriers occurs through what's called the channelofan FET. FET channels are created within the bulk material of the FET, which is usually silicon.
Some specific types of FETs:
CNTFET - carbon nanotube field-effect transistor - These FETs use carbon nanotubes instead of silicon as their channel material. Carbon nanotubes are needed as FETs continue to get smaller in size. They help reduce effects, such as quantum tunneling and overheating, which are beginning to become real problems in small, silicon-based FETs.
JFET - junction gate field-effect transistor - This FET supplies a voltage accross the charge-carrying channel that can pinch it shut, effectively stopping the current through the channel.
MESFET - metal semiconductor field-effect transistor - Similar to, but faster than, JFETs, MESFETs use a Schottky barrier (see above) instead of a PN junction.
HEMT - high electron mobility transistor - The FET version of an HBT (see above). Faster than a MESFET, the charge-carrying channel is between two different materials instead of within a single, doped region. Also known as a heterostructure FET (HFET) or a modulation-doped FET (MODFET).
MOSFET - metal-oxide-semiconductor field-effect transistor - This is the most basic, and most common, type of FET, analogous to the standard BJT (see above). Instead of pinching its charge-carrying channel shut as in a JFET, a MOSFET has an insulator attached to its input electrode which can be turned on or off depending on whether a voltage is supplied accross it. The channel can be N-type (nMOS) or P-type (pMOS), as explained above under the "bipolar junction transistors" heading.
ITFET - inverted-T field-effect transistor - This is simply any type of FET that extends vertically out from the horizontal plane in a T-shape, hence the name.
MuGFET - multiple gate field-effect transistor - A MOSFET where more than one input shares the bulk material of the FET. The idea is to use the same FET, thus the same sized object, for multiple things. This concept came about due to the ever shrinking sizes of transistors.
MIGFET - multiple independent gate field-effect transistor - A MuGFET where the multiple inputs are independently controlled.
Flexfet - A MIGFET with two inputs, one on a JFET and the other on a MOSFET. The JFET and MOSFET are then "stacked" on top of each other. Due to its design, the JFET and MOSFET are coupled to each other; i.e. the channel through one effects the channel through the other and vice versa.
FinFET - A MuGFET where the charge-carrying channel is wrapped around a piece of silicon, called a fin. The reason for doing this is similar to that of a PADT (see above); i.e. mechanical strength.
FREDFET - fast-recovery (or reverse) epitaxial diode field-effect transistor - A cute name for a transistor which is basically designed to quickly turn off when no more voltage is being supplied to it.
TFT - thin-film transistor - An FET where the semiconducting material is placed via thin films over the bulk of the device. This is opposed to the bulk of the device being the semiconductor itself, as in most FETs. The bulk material used in TFTs is often glass. The reason being so that the transistors can work behind a clear display in applications like liquid crystal display (LCD) monitors.
OFET - organic field-effect transistor - An FET with an organic polymer semiconductor as its channel. These are like TFTs except the bulk of the device is plastic, allowing for very cool, flexible LCD monitors.
FGMOS - floating gate MOSFET - A MOSFET with a "floating gate" input; i.e. an electrically isolated input that can store charge, like a capacitor, to be used later. These are the transistors behind flash drives.
ISFET - ion-sensitive field-effect transistor - An FET that changes its current depending on the ion concentration of a solution. The solution itself is used as the input electrode in an ISFET.
EOSFET - electrolyte-oxide-semiconductor field-effect transistor - A MOSFET with the metal replaced by an electrolyte solution. EOSFETs are used to in neurochips to detect brain activity.
DNAFET - Deoxyribonucleic acid (DNA) field-effect transistor - A MOSFET with its input electrode being a layer of immobilized, single-stranded DNA. The current through the MOSFET is modulated by the varying charge distributions that occur when complimentary DNA strands hybridize to the layer of single-stranded DNA on the input electrode. DNAFETs are used, not surprisingly, in DNA sequencing.
Connection of Transistors: - Transistors have three leads which must be connected the correct way round. Please take care with this because a wrongly connected transistor may be damaged instantly when you switch on.
If you are lucky the orientation of the transistor will be clear from the PCB or stripboard layout diagram, otherwise you will need to refer to a supplier's catalogue to identify the leads.
The drawings above show the leads for some of the most common case styles. Please note that transistor lead diagrams show the view from below with the leads towards you. This is the opposite of IC (chip) pin diagrams which show the view from above.
Soldering
Transistors can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the transistor body. A standard crocodile clip can be used as a heat sink. Heat Sink
Waste heat is produced in transistors due to the current flowing through them. Heat sinks are needed for power transistors because they pass large currents. If you find that a transistor is becoming too hot to touch it certainly needs a heat sink! The heat sink helps to dissipate (remove) the heat by transferring it to the surrounding air.
Transistors Codes Codes beginning with B (or A), for example BC108, BC478.The first letter B is for silicon, A is for germanium (rarely used now). The second letter indicates the type; for example C means low power audio frequency; D means high power audio frequency; F means low power high frequency.The rest of the code identifies the particular transistor. There is no obvious logic to the numbering system. Sometimes a letter is added to the end (e.g. BC108C) to identify a special version of the main type, for example a higher current gain or a different case style. If a project specifies a higher gain version (BC108C) it must be used, but if the general code is given (BC108) any transistor with that code is suitable. Codes beginning with TIP, for example TIP31A .TIP refers to the manufacturer: Texas Instruments Power transistor. Odd numbers are NPN, even numbers are PNP. The letter at the end identifies versions with different voltage ratings.
Codes beginning with 2N, for example 2N3053.The initial '2N' identifies the part as a transistor and the rest of the code identifies the particular transistor. There is no obvious logic to the numbering system.
Choosing a transistor
Most projects will specify a particular transistor, but if necessary you can usually substitute an equivalent transistor from the wide range available. The most important properties to look for are the maximum collector current IC and the current gain hFE. To make selection easier most suppliers group their transistors in categories determined either by their typical use or maximum power rating.
To make a final choice you will need to consult the tables of technical data which are normally provided in catalogues. They contain a great deal of useful information but they can be difficult to understand if you are not familiar with the abbreviations used. The table below shows the most important technical data for some popular transistors, tables in catalogues and reference books will usually show additional information but this is unlikely to be useful unless you are experienced. Testing of Transistor
Transistor can be damaged by heat when soldering or by misuse in a circuit. If you suspect that a transistor may be damaged.
Testing with multimeter.
Use a multi meter or a simple tester (battery, resistor and led) to check each pair of leads for conduction. Set a digital multimeter to a low resistance range.
Test each pair of leads both ways (Six tests in total):
The base-emitter (BE) junction should behave like a diode and conduct one way only. The base-collector (BC) junction should behave like a diode and conduct one way only. The collector-emitter (CE) should not conduct either way.
Function of Transistor: - 1. Switching: -
2. Amplification: -
3. Regulation: -
IC: - INTEGRATION OF CIRCUIT
DEF: -An integrated circuit (IC), sometimes called a chip or microchip, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated. An IC can function as an amplifier, oscillator, timer, counter, computer memory, or microprocessor. A particular IC is categorized as either linear (analog) or digital, depending on its intended application.
Linear ICs have continuously variable output (theoretically capable of attaining an infinite number of states) that depends on the input signal level. As the term implies, the output signal level is a linear function of the input signal level. Ideally, when the instantaneous output is graphed against the instantaneous input, the plot appears as a straight line. Linear ICs are used as audio-frequency (AF) and radio- frequency (RF) amplifiers. The operational amplifier (op amp) is a common device in these applications.
Digital ICs operate at only a few defined levels or states, rather than over a continuous range of signal amplitudes. These devices are used in computers, computer networks, modems, and frequency counters. The fundamental building blocks of digital ICs are logic gates, which work with binary data, that is, signals that have only two different states, called low (logic 0) and high (logic 1).
INTEGRATION OF I.C.: -
No of transistor used in an i.c. is called integration of I.C.
TYPE OF INTEGRATION:- SSI (small-scale integration): Up to 100 electronic components per chip. MSI (medium-scale integration):From 100 to 3,000 electronic components per chip. LSI(large-scale integration):From 3,000 to 100,000 electronic components per chip. VLSI(very large-scale integration):From 100,000 to 1,000,000 electronic components per chip. ULSI(ultra large-scale integration):Morethan 1 million electronic components per chip.
Soldering
How to Solder
First a few safety precautions:
Never touch the element or tip of the soldering iron. They are very hot (about 400°C) and will give you a nasty burn.
Take great care to avoid touching the mains lead with the tip of the iron. The iron should have a heatproof lead for extra protection. An ordinary plastic lead will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.
Always return the soldering iron to its stand when not in use. Never put it down on your workbench, even for a moment!
Work in a well-ventilated area. The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.
Wash your hands after using solder. Solder contains lead which is a poisonous metal.
Preparing the soldering iron:
Place the soldering iron in its stand and plug in. The iron will take a few minutes to reach its operating temperature of about 400°C.
Dampen the sponge in the stand. The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.
Wait a few minutes for the soldering iron to warm up. You can check if it is ready by trying to melt a little solder on the tip.
Wipe the tip of the iron on the damp sponge. This will clean the tip.
Melt a little solder on the tip of the iron. This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge.
Soldering Step by Step
Hold the soldering iron like a pen, near the base of the handle. Imagine you are going to write your name! Remember to never touch the hot element or tip.
Touch the soldering iron onto the joint to be made. Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and.
Feed a little solder onto the joint. It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron.
Remove the solder, then the iron, while keeping the joint still. Allow the joint a few seconds to cool before you move the circuit board.
Inspect the joint closely. It should look shiny and have a 'volcano' shape. If not, you will need to reheat it and feed in a little more solder. This time ensure that both the lead and track are heated fully before applying solder.
Using a Heat Sink
Some components, such as transistors, can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the component body. You can buy a special tool, but a standard crocodile clip works just as well and is cheaper.
Further Information For a much more detailed guide to soldering, including troubleshooting, please see the Basic Soldering Guide on the everyday practical electronics magazine website.
Desoldering At some stage you will probably need to desolder a joint to remove or re-position a wire or component. There are two ways to remove the solder: 1. With a desoldering pump (solder sucker)
Set the pump by pushing the spring-loaded plunger down until it locks. Apply both the pump nozzle and the tip of your soldering iron to the joint. Wait a second or two for the solder to melt. Then press the button on the pump to release the plunger and suck the molten solder into the tool. Repeat if necessary to remove as much solder as possible.
The pump will need emptying occasionally by unscrewing the nozzle. Using a desoldering pump (solder sucker)
2. With solder remover wick (copper braid)
Apply both the end of the wick and the tip of your soldering iron to the joint. As the solder melts most of it will flow onto the wick, away from the joint. Remove the wick first, then the soldering iron. Cut off and discard the end of the wick coated with solder
Lesson -4
SMPS Power supply Types of SMPS Working Power Connectors Troubleshooting
A switch mode power supply commonly known as S.M.P.S is a power source for all the electronic components in the computer. Generally it acts as AC toDC converter. The SMPS act as a multiple Dc source providing a variety of voltages & currents .commercially available SMPS is of two types namely AT(Advanced technology) & ATX(Extended advanced technology).
A switched-mode power supply (SMPS) is a type of power regulator that is able to quickly adjust the amount of electricity being provided. This feature allows a SMPS to be very efficient and avoid energy waste. The general purpose of this power supply is to receive electricity from an external source, and convert the power to a level required by a load. Switched-mode power supplies are commonly used in personal computers.
Most personal computers in earlier days used linear regulators. These earlier power units produced a set, unvaried amount of voltage. In order to keep this output constant, linear supplies typically used simple resistors. This generated a significant amount of heat, and wasted voltage during the regulation process.
Switched-mode power supplies solve this problem and do not waste energy in the form of heat. Instead of regulating voltage through resistors, a SMPS is equipped with several different transistors and capacitors. The power supply can quickly select a combination of components that is the most efficient for a specific situation. In essence, a switched-mode power supply can provide the exact amount of voltage that is demanded by a load.
In addition to the advantage of efficiency, a switched-mode power supply has several additional advantages. A SMPS is usually smaller and more lightweight than a comparable linear model, due to the lack of bulky transformers. Switched-mode supplies are less prone to overheating, and often have a longer usable life than their linear counterparts.
Computers are the most common devices that use switched-mode power supplies, but other devices also make use of them. Many cell phone chargers are in fact small SMPS units. This allows them to efficiently convert wall power without becoming overheated. A switched-mode supply can be used in practically any application where high efficiency is required
Type of SMPS according to technology:-
1. AT (Advance Technology) 2. ATX (Advance Technology Extended)
WORKING PRINCIPLE: -
The 230v AC supply is applied to the line filter circuit via the double pole single throw switch (DPST) and the fuse. The input AC voltage is filtered and this is applied to the bridge rectifier section. The rectifier section converts the given AC input into DC. The filtering circuitry consists of capacitor and resister. Approximately 300v‘s of output DC supply is obtained. This is due to rectifier section as the voltage is increased by 1.414 times the input by the diodes. This 300v Dc supply is obtained from the common cathode terminal, and the common anode terminal is connected to the floating ground. The middle terminal provides +/- 150v. This output is applied to the switching section that is to collector of the first switching transistor. The switching circuit contains two transistors with the emitter coupled to the other collector. The transistors are of same specifications. The switching circuit is activated by a ‗start circuit‘ which provides initiating pulses for short duration. Once the switching circuits starts functioning voltage is developed across the secondary side of the SM transformer, which is converted to Dc by diode & filter. A reference voltage is applied to the error amplifier circuit. This compare the given input DC supply & finally sends signal to oscillator section. According to the sends signal of error amplifier the oscillator selects appropriate frequency which is then applied to the driver section. This drives the switching transistors at the selected frequency. Here the output is regulated until power is off. A power good circuit supervises the output. This sends the signal to the mother board only with the output voltage is constant if minimal error. If not the mother board doesn‘t use the supply.
Circuit diagram of ATX SMPS
Working Principle of Each section of ATX SMPS
INPUT SECTION
The input of 220v AC supply is given to the switch. The fuse acts as a protective circuitry to protect the circuit from over voltage spikes. The thyristor is of NTC type (negative temperature co-efficient). Here as the temperature increases the conductivity and resistance decreases. This types of behavior protect the circuit from sudden voltage variations. Similarly the inductor assembly provides a constant supply of
Voltages to the line filter assembly consisting of capacitors. These filter the Dc components from the AC inputs and give the filtered AC supply to the bridge rectifier assembly. The output is drawn from the common anode point giving –ve output with respect to the +300v output which is drawn from the common cathode terminal of the rectifier section. The middle terminal gives +/-150v output. Moreover the rectifier section is followed by an array of electronic capacitors (C5, C6) and resistors (R2, R3) parallel to it. The capacitors store the charge and provide a constant output while the resistors act as an external load to the circuitry.
SWITCHING SECTION
The input of 300v AC is applied to the collector terminal of first transistor T1. This is called the switching transistors. Generally two transistors of same specifications are used in this section. They can be of type C4242, C3039, C5027, C3225, 13007, 13005. These transistors are biased by the resistors R1 & R2 along with R5 & R7. Generally in ATX type of SMPS the resistors R3 & R5 are absent and the resistors R9 & R10 are replaced by diodes. The switching transistors are driven from the signaling of driver section. This gives in appropriate pulses as send by the oscillators and error amplifier. The start signaling is only for a short time. The emitter of a transistor T2 is connected to the floating ground. The emitter of first transistor is coupled to the collector of second transistor. Approximately a voltage of 165 v is impressed at the emitter of T1. The coupling point of the transistors is connected to the protector transformer, which is connected to the SM transformer. Generally the SM transformer has inbuilt protector windings. The other end of SM transformer has the supply from the +/- 150v supply coming from the input section. As the switching transistor T1 starts functioning a –ve voltage is developed at the upper end of the primary of SM transformer and a +ve voltage is developed across the lower end. Similarly if the transistor T2 conducts reverse voltages are developed on the primary side. As the transistor switch an AC voltage of 165v is developed on the primary side of SM transformer. This is induced on the secondary side and distributed in two parts. Thecentre tapped winding gets a voltage of 5v & the other gets a voltage of 12v. The switching section operates at a frequency of 20 to 40 kHz.
Output section
This section gets the input from SM transformer. The CT type winding in the secondary winding of SM transformer with 5v supply is given as input to a double diode with common cathode for rectification. The common cathode is coupled with two diodes D1, D2 and fed in a parallel set of inductor L3 that acts as a constant current source. The output of +5v is obtained from this line. It carries a current of 30A. In some ATX SMPS the inductor L6 is absent along with the capacitor C5 and the resistor R4. The common anode terminal is coupled to two diodes D1, D2 which is connected to inductor L3 and L7. This terminal gives -5v with 0.8 a current. The next winding of Sm transformer with 12v is fed to the next double diode. This diode again serves as a rectifier. This is of common cathode types. The common anode terminal is fed into inductor assembly L4 and L8. This terminal again gives output of +12v DC/12A, while the common cathode terminal is fed into L5, L9 which again gives an output of -12v DC/0.8A.
DRIVER SECTION
This section gets the input from the oscillator section and the error amplifier section. These sections are responsible for regulating the output by generating frequencies between 20 to 40 KHz. This is used to drive the switching section at a definite switching frequency. The oscillator, error amplifier & comparator are inbuilt in an integrated circuitary i.e. IC 494, or KA 7500 is used then the input to the two transistors is from the 8 & 11 pin of the IC. While if the IC 2003 is used then the input is taken from the 7 & 8of the IC. Again an input of 12v DC is applied to the centre tap of driver transformer via a booster diode.
Applying input from the 8th pin causes a –ve potential to developed at the upper end of the delivered transformer and applying signal from the 11th pin to the base of the transistor Q2 a +ve potential is developed across the upper end of the transistor. The two transistors are emitter coupled and the resistor R1, R2, R3 and R4 do base biasing. D1 and D2 are used to protect the transistor from over voltages. A reference voltage is applied to the error amplifier. This gets the signal from comparator, which compares the output to desired value. According to the signaling of the error amplifier the oscillator selects the correct frequency to be applied to the driver transformer. The two transistors drive the transformer, which in turn drives the switching section. Hereby the power is regulated until the power is off.
STANDBY SECTION
This section consists of two transistors which gives the supply to the primary winding of the double transformer. The two transistors are coupled with the collector of one coupled to the base of others. An input of +300v is applied to the primary winding of the doubler transformer as well as the base of transistor via R1 which is of very high wattage. Thedoubler transformer has two windings at the primary side and is grounded by floating ground via the emitter of Q2.
The standby section activates the APM circuitry(Advanced Power Management). The input to the transformer is 220v and the output is 5v. The zener diode acts as a voltage regulator restricting the circuitry to 6v. It is to be noted that only one winding of double transformer is activated at a time and this section is connected to the oscillator circuitry by the power on terminal.
OSCILLATOR ERROR AMPLIFIER AND POWERGOOD
In TL494, connecting an external timing circuit consisting of a resistor to the pin number 5& 6 controls oscillator frequency. The oscillator is set to operate at about 20 to 40 KHz of frequency.
Error amplifier:The error amplifier circuitry is used to compare the output signal from the 5v and 12 v port through a reference pin & adjusts a pulse width modulator(PWM) to maintain a constant output voltage.
Soft start: The soft start allows the pulse width at output to increase slowly by applying a -ve sloped waveform the dead time control at the pin numbered 4 and 14, which initially force the output to near desired condition. As the capacitor charges up to its optimum value the pulse width slowly increases.
Output: The output of TL494 IC is available at the pin numbered 8 & 11 for the push pull operation and are connected to two number of driver transistors. Primary of the driver transformer are centre tap and switch alternately by this transistor and producing suitable base drive pulses to two power transistors.
Power good: Its main function is to compare the reference voltage with the aid of the operational amplifier.
This operational amplifier gives the output only if the difference between the two signals at the input terminal is 7v and if the output is constant with no voltage spikes. This power good section is inbuilt in the IC2003, which acts as an error amplifier, oscillator and comparator along with the power good section. The power good gives supply to the mother board only if the output voltages of the SMPS are constant and not fluctuating.
Pin Configuration of AT Mother Board connector: -
Pin-1 PG the Voltage is 4 to 6 volt. Pin-7 Ground Pin-2 + 5 Volt Pin-8 Ground Pin-3 +12 Volt Pin-9 -5 Volt Pin-4 -12 Volt Pin-10 +5 Volt Pin-5 Ground Pin-11 +5 Volt Pin-6 Ground Pin-12 +5 Volt
Standardized colored wired present in output of AT SMPS:
RED = + 5Volt WHITE= -5Volt
YELLOW= +12Volt ORANGE= PG
BLUE= -12Volt BLACK= GROUND
PIN CONFIGURATION OF 20 PIN MOTHERBOARD CONNECTOR: -
This power connector is used to give power supply to the motherboard. It is of two type 20 pin and 24 pin. We can use according to port present on the motherboard.
Pin-1 +3.3 Volt Pin-11 +3.3 Volt Pin-2 +3.3 Volt Pin-12 - 12 Volt Pin-3 Ground Pin-13 Ground Pin-4 + 5 Volt Pin-14 Power On Pin-5 Ground Pin-15 Ground Pin-6 + 5 Volt Pin-16 Ground Pin-7 Ground Pin-17 Ground Pin-8 PG(Power Good) 4-6 V Pin-18 -5Volt Pin-9 + 5Volt Stand By Pin-19 + 5 Volt Pin-10 + 12 Volt Pin-20 + 5 Volt
Molex: - It is four pin connector, which gives power supply to ID devices (CD drive, HDD). Voltage are +12V, +5V, 2 no of ground. Now for the SATA device there is SATA power connector. If there is no SATA connector then we can use Molex to SATA converter.
Burze: - It is also four pin connector, which gives power supply to floppy disk drives.Voltage are +12V, +5V, 2 no of ground.
Core Voltage Connector: - It is used to provide the extra +12V directly to the mother board. In P4 mother only it is present.
SMPS Troubleshooting Most Common Problems The following probably account for 95% or more of the common SMPS ailments:
Supply dead, fuse blown - shorted switch-mode power transistor and other semiconductors, open fusable resistors, other bad parts. Note: actual cause of failure may be power surge/brownout/lightning strikes, random failure, or primary side electrolytic capacitor(s) with greatly reduced capacity or entirely open - test them before powering up the repaired unit. Supply dead, fuse not blown - bad startup circuit (open startup resistors), open fusable resistors (due to shorted semiconductors), bad controller components. One or more outputs out of tolerance or with excessive ripple at the line frequency (50/60 Hz) or twice the line frequency (100/120 Hz) - dried up main filter capacitor(s) on rectified AC input. One or more outputs out of tolerance or with excessive ripple at the switching frequency (10s of kHz typical) - dried up or leaky filter capacitors on affected outputs. Audible whine with low voltage on one or more outputs - shorted semiconductors, faulty regulator circuitry resulting in overvoltage crowbar kicking in, faulty overvoltage sensing circuit or SCR, faulty controller. Periodic power cycling, tweet-tweet, flub-flub, blinking power light - shorted semiconductors, faulty over voltage or over current sensing components, bad controller.
In all cases, bad solder connections are a possibility as well since there are usually large components in these supplies and soldering to their pins may not always be perfect. An excessive load can also result in most of these symptoms or may be the original cause of the failure. And don't overlook the trivial: a line voltage select switch in the wrong position or between positions (possibly by accident when moving the supply, particularly with PCs), or damaged.
Lesson -6
Motherboards and Add-on Cards
Motherboard
The motherboard serves to connect all of the parts of a computer together. The CPU, memory, hard drives, optical drives, video card, sound card and other ports and expansion cards all connect to the motherboard directly or via cables. The motherboard can be thought of as the "back bone" of the computer.
The Motherboard is Also Known As mainboard, mobo (abbreviation), MB (abbreviation), system board, logic board.
Important Motherboard Facts: Motherboards, cases and power supplies all come in different sizes called form factors. All three must be compatible to work properly together. Motherboards vary greatly in respect to the types of components they support, so each component must be compatible in order for it to work properly. CPUs have specific socket types which match with a motherboard. If an incompatible socket type is used, the CPU will not even fit onto the board. CPUs also have front side bus speeds that need to work with the motherboard. The front side bus is the speed at which the CPU can access the RAM. Having differing front side bus speeds can cause the CPU to either be overrun or not work to its full efficiency. The motherboard also uses specific types of RAM, so using incompatible ones could cause a system to not work at all.
Why Is a Motherboard Necessary?
Without the motherboard, each component would be unable to communicate with the other. For example, a CPU uses the RAM to run applications that are stored on the main hard drive, but in order to do so, each component is connected to the motherboard, which regulates the information flow. The motherboard acts like a command centre that helps direct what each component does and when it can do it. This ensures that the system will run smoothly.
Popular Motherboard Manufacturers:
ASUS, AOpen, Intel, ABIT, MSI, Gigabyte, Biostar
Types of Computer Motherboards
There are different ways to classify motherboards, which are:
Configuration:-
Integrated Motherboard:-Peripheral device slots, serial parallel ports and input output ports are other physical components or parts that are involved in the working of a computer. When such components are provided for by the motherboard, i.e. they are built into the motherboard, the motherboard is called integrated.
Nonintegrated Motherboard: - External devices card install into the pcs slots. It not builds the chip for the peripheral devices. The old pc uses the non-integrated motherboard.
Application:-
Desktop Motherboard: - Its uses for desktop pc and in middle size.Desktop motherboards have only one socket for a processor. Smaller than server ones and a lot cheaper. Less sockets for RAM and PCI-E Laptop Motherboard: - Its uses for laptop and small in size than desktop and server Motherboard.Each laptop, with its unique motherboard layout, sacrifices expansion to allow for ever-thinner and lighter models. Server Motherboard: - It is made for only server computer. It is large in size.Server motherboards usually have dual sockets for processors. Huge and can‘t fit in normal computer cases. A lot of slots for RAM and PCI-E.
Construction(Manufacturer):-
Chipset Motherboard:-The board and chips manufacturer company are different. Original Motherboard:-The board and chip Manufacturer Company are same.
Form factor of the Motherboard:- The shape and layout of a motherboard is called the form factor. The form factor affects where individual components go and the shape of the computer's case. There are several specific form factors that most PC motherboards use so that they can all fit in standard cases.
Old:-ObsoleteForm and Factor. 1. PC/XT: -He who is first shall be last. The PC/XT form factor was the first "official" form factor. It originated with the first desktop PC the IBM PC. The clone marketed erupted thanks to IBM's wise decision to go with an open architecture, and the PC/XT form factor became the defacto standard. At least until the AT form factor was introduced.
2. Baby AT:-The Baby AT was the standard in the PC industry from roughly 1993-1997. Some issues with the AT and Baby AT design is the location of the features on the board. The CPU socket is placed so that it may interfere with longer bus cards. In some designs the memory sockets are similarly placed. This can limit the amount and selection of peripheral cards you can install. Also the IO ports are separate and mounted on the case and connected to pin-outs on the motherboard. These are usually located near the floppy and IDE pin-outs and can result in quite a jumble of ribbon cables.
3. Full size AT:- The AT (also called Full AT) form factor is the oldest and the biggest form factor. It was popular until the Baby AT was released, which was around the time of the 386 processor (1992-93). The reason that prompted the Baby AT was the width of the AT (12") and the fact that the board was difficult to install, service, and upgrade.
4. LPX (Low profile Extended): -This is based on a design by Western Digital. The expansion slots are on a single riser card which is mounted onto the planar board. Mainly OEM manufacturers (i.e. Packard Bell/NEC, Dell, etc) use these boards. The distinguishing characteristic of LPX is that expansion boards are inserted into a riser that contains several slots. So the expansion boards are parallel to the motherboard rather than perpendicular to it as in other common form factors, such as AT and ATX. The LPX design allows for smaller cases, but the number of expansion boards is usually limited to two or three.
5. NLX (New Low-Profile Extended): -A low-profile PC motherboard from Intel for slimline cases, introduced in 1987. Unlike boards for desktop and tower cases that hold the expansion cards perpendicular to the board, cards plug into a riser card on the NLX and are parallel with the board.
6. WTX ( Workstation Technology Extended): - This motherboard was introduced by Intel at the IDF in September 1998, for its use at high-end, multiprocessor, multiple-hard-disks server and workstations. The specification had support from major OEMs (Compaq, Dell, Fujitsu, Gateway, Hewlett-Packard, IBM, Intergraph, NEC, Siemens Nixdorf, and UMAX) and motherboard manufacturers (Acer, Asus, Supermicro and Tyan). OEM: -Original equipment manufacturer.
7. BTX (Balance Technology Extended): - Intel has collaborated with the Desktop Computing industry to create an evolutionary step in the desktop computer form factor. Balanced Technology Extended (BTX) integrates cost-effective engineering and design strategies for power dissipation, structural integrity, acoustic performance, and motherboard design into a scalable form factor.BTX also allows for multiple board sizes utilizing a common core: BTX: maximum width 325.12 mm, up to 7 add-in card slots MicroBTX: maximum width 264.16 mm, up to 4 add-in card slots PicoBTX: maximum width 203.20 mm, up to 1 add-in card slot
Modern Form and Factor.
ATX: -ATX was developed(introduced in 1995) as an evolution of the Baby AT form factor and was defined to address four areas of improvement: enhanced ease of use, better support for current and future I/O, better support for current and future processor technology, and reduced total system cost. As of 2007, it is the most popular form factor for commodity motherboards. Typical size is 9.6 × 12 in although some companies extend that to 10 × 12 inches.
MicroATX: - A smaller variant of the ATX form factor (about 25% shorter). Compatible with most ATX cases, but has fewer slots than ATX, for a smaller power supply unit. Very popular for desktop and small form factor computers as of 2007.
MiniATX: -Mini-ATX is slightly smaller than Micro-ITX. Mini-ATX motherboards were design with MoDT (Mobile on Desktop Technology) which adapt mobile CPUs for lower power requirement, less heat generation and better application capability.
FlexATX: -A subset of the microATX design. FlexATX offers the opportunity for system developers to create many new personal computer designs. FlexATX allows enhanced flexibility where conforming motherboards may be enclosed; that is, all-in-one computing devices, LCD-personal computers, or standard desktop systems.This form factor is designed to allow very custom case and board designs to be manufactured.
ITX (Industrial Telecommunication extended): - The idea of the ITX motherboard is to have everything on-board, making the installation of new peripherals needless. So its size is a lot reduced, since there is not the need of having many expansion slots.
MiniITX: -The Mini-ITX mainboard form factor is a highly integrated native x86 mainboard measuring only 170mm x 170mm and enables the development of an infinite variety of small form factor PC systems. More than 33% smaller than the FlexATX mainboard form factor, the Mini-ITX is aimed at the development of Thin-Clients, wireless network devices, digital media systems, set-top boxes and more.
DTX: -The DTXform factor is a variation of ATX specification[1] designed especially for small form factor PCs (especially for HTPCs) with dimensions of 8.0 by 9.6 inches (converted to 203 mm by 244 mm) An industry standard intended to enable interchangeability for systems similar to Shuttle's original "SFF" designs,AMD announced its development on January 10, 2007. AMD stated that the DTX form factor is an open standard, and is backward compatible with ATX form factor cases. They also present a shorter variant named Mini-DTX which is smaller in PCB size of 203 mm by 170 mm (8.0 by 6.7 inches.)
Components on the motherboard: -
CPU Socket: - The CPU is installed in either a socket or a slot, depending on the type of chip. Starting with 486 processor, Intel designed the processor to be a user-installable and replaceable part and developed standards for CPU sockets and slots that would allow different models of the same basic processor to plug in. The introduction of the ZIF (Zero Insertion Force) socket for PGA types allowed the CPU's to be lined up without any pressure on the CPU until a level is pulled down.The newest Intel CPU does not have a PGA. It has an LGA, also known as Socket T. LGA stands for Land Grid Array. An LGA is different from a PGA in that the pins are actually part of the socket, not the CPU.Different socket types accepted different families of processors. If you know the type of socket or slot on your motherboard, you essentially know which types of processor are designed to plug in.
Commonly used sockets are:
Socket 478 - for older Pentium and Celeron processors. Socket 939 - for newer and faster AMD Athlon processors. Socket AM2 - for the newest AMD Athlon processors. LGA775/Socket T – for new Pentium 4, Pentium D, Core 2 Duo, Core 2 Quad and Xeon. LGA 1155/Socket H2- for Intel Sandy Bridge Intel Ivy Bridge. LGA 1150/Socket H3 – for newest processor Intel Haswell Intel Broadwell.
Chipset A chipset is a collection of chips or circuits that perform interface and peripheral functions for the processor. This collection of chips is usually the circuitry that provides interfaces for memory, expansion cards, and onboard peripherals and generally dictates how a motherboard will talk to the installed peripherals.
Chipsets are usually given a name and model number by the original manufacturer. The functions of chipsets can be divided into two major functional groups, called North-bridge and Southbridge. Let‘s take a brief look at these groups and the functions they perform.
Northbridge
The Northbridge subset of a motherboard‘s chipset is the set of circuitry or chips that performs one very important function: management of high-speed peripheral communications. The Northbridge subset is responsible primarily for communications with integrated video using AGP and PCIe, for instance, and processor-to-memory communications. Therefore, it can be said that much of the true performance of a PC relies on the performance of the Northbridge chipset and the communications between it and the peripherals it controls. The communications between the CPU and memory occur over what is known as the front-side bus (FSB), which is just a set of signal pathways between the CPU and main memory. The backside bus, on the other hand, is a set of signal pathways between the CPU and Level 2 cache memory (if present). The Northbridge chipsets also manage the communications between the Southbridge chipset (discussed next) and the rest of the computer. Finally, if a motherboard has onboard video circuitry (especially if it needs direct access to main memory), that circuitry will be found within the Northbridge chipset.
Chipset Manufacturer: - Intel, VIA, SIS, ATI
Future of chipset: - The Intel new series of chipsets is designed to support the original Core i Series processors. These processors and chipsets have a distinctly different design from previous Intel chipsets and represent anew level of system integration. Perhaps the biggest difference between the mew series chipsets and its predecessors is that the memory controller is no longer part of the chipset, having been moved directly into the Core i Series processors instead. Placing the memory controller in the processor means that the memory modules are directly connected to the processorinstead of the North Bridge chipset component, allowing for a dedicated connection between the processor and memory. With the memory controller integrated into the processor, the only function left for the North Bridge is to act as an interface to the PCIe video card slots. Because the North Bridge no longer controls memory, Intel changed the name from MCH to IOH (I/O Hub) in the new series chipsets.
Below first picture is of old motherboard with MCH and second picture is of new motherboard without MCH.
FSB and BSB A bus is simply a circuit that connects one part of the motherboard to another. The more data a bus can handle at one time, the faster it allows information to travel. The speed of the bus, measured in megahertz (MHz), refers to how much data can move across the bus simultaneously. Bus speed usually refers to the speed of the front side bus(FSB), which connects the CPU to the Northbridge. FSB speeds can range from 66 MHz to over 1600 MHz Since the CPU reaches the memory controller though the Northbridge, FSB speed can dramatically affect a computer's performance. The back side bus (BSB) connects the CPU with the level 2 (L2) cache, also known as secondary or external cache. The processor determines the speed of the back side bus.
Southbridge The Southbridge chipset, as mentioned earlier, is responsible for providing support to the myriad onboard peripherals (PS/2, Parallel, IDE, and so on), managing their communications with the rest of the computer and the resources given to them. Most motherboards today have integrated PS/2, USB, Parallel, and Serial. Some of the optional features handled by the Southbridge include LAN, audio, infrared, and FireWire (IEEE 1394). When first integrated, the quality of onboard audio was marginal at best, but the latest offerings (such as the AC97 audio chipset) rival Creative Labs in sound quality and number of features (even including Dolby Digital Theater Surround technology). The Southbridge chipset is also responsible for managing communications with the other expansion buses, such as PCI, USB, and legacy buses.
BIOS (Basic Input Output System) Chip The BIOS holds the most important data for your machine, if configured incorrectly it could cause your computer not to boot correctly or not at all. The BIOS also informs the PC what the motherboard supports in terms off CPU etc. This is why when a new CPU is introduced that physically fits into a slot or socket you may need a BIOS update to support it. The main reason for this is that different CPU's use different logics and methods and so the BIOS has to understand certain instructions from the CPU to recognize it.
Memory slot A memory slot, memory socket, or RAM slot is what allows computer memory (RAM) to be inserted into the computer. Depending on the motherboard, there will usually be 2 to 4 memory slots (sometimes more on high-end motherboards) and is what determine the type of RAM used with the computer.
When buying a new computer or motherboard, pay close attention to the types of RAM the memory slots will allow to be used, so you are familiar with what type of RAM to buy for your computer.
Detail about the RAM and memory module is given in ―Primary Memory‖ chapter.
Expansion Slots
The most visible parts of any motherboard are the expansion slots. These look like small plastic slots, usually from 3 to 11 inches long and approximately 1/2 inch wide. As their name suggests, these slots are used to install various devices in the computer to expand its capabilities. Some expansion devices that might be installed in these slots include video, network, sound, and disk interface cards.
ISA Expansion Slots
If you have a computer made before 1997, chances are the motherboard has a few Industry Standard Architecture (ISA) expansion slots. They‘re easily recognizable because they are usually black and have two parts: one shorter and one longer. Computers made after 1997 generally include a few ISA slots for backward compatibility with old expansion cards (although most computers are phasing them out in favour of PCI).ISA slots are two types 8-bit ISA and 16-bit ISA. 8 - bitISAhas 62 numbers of contact line & is found in 8088 mother board.16 – bit ISA having 98 numbers of contact line & is found in 386, 486 P- i, P- ii, P – iii mother board. In ISA slot you can connect display, lan, sound card etc.
PCI Expansion Slots
Most computers made today contain primarily Peripheral Component Interconnect (PCI)slots. They are easily recognizable because they are short (around 3 inches long) and usually white. PCI slots can usually be found in any computer that has a Pentium-class processor or higher. 32-bit PCI -It has 120 nos. of contact lines & is found in 486,P-i,P-ii,P-iii,P-iv mother board. 64- bit PCI –It has 162 nos. of contact lines & is found in some costlier p-iv mother board like 915,945,965 etc. here we can connect all most all types of card.
AGP Expansion Slots
Accelerated Graphics Port (AGP) slots are very popular for video card use. In the past, if you wanted to use a high- speed, accelerated 3D graphics video card, you had to install the card into an existing PCI or ISA slot. AGP slots were designed to be a direct connection between the video circuitry and the PC‘s memory. They are also easily recognizable because they are usually brown, are located right next to the PCI slots on the motherboard, and are shorter than the PCI slots. Figure 1.6 shows an example of an AGP slot, along with a PCI slot for comparison. Notice the difference in length between the two.
PCIe Expansion Slots
The newest expansion slot architecture that is being used by motherboards is PCI Express (PCIe). It was designed to be a replacement for AGP and PCI. It has the capability of being faster than AGP while maintaining the flexibility of PCI. And motherboards with PCIe will have regular PCI slots for backward compatibility with PCI. There are seven different speed levels for PCIe, and they are designated 1X, 2X, 4X, 8X, 12X, 16X, and 32X. These designations roughly correspond to similarly designated AGP speeds. The slots for PCIe are a bit harder to identify than other expansion slot types because the slot size corresponds to its speed. For example, the 1X slot is extremely short (less than an inch). The slots get longer in proportion to the speed; the longer the slot, the higher the speed. The reason for this stems from the PCIe concept of lanes, which are the multiplied units of communication between any two PCIe components and are directly related to physical wiring on the bus. Because all PCIe communications are made up of unidirectional coupling between devices, each PCIe card negotiates for the best mutually supported number of lanes with each communications partner.
AMR Expansion Slots
As is always the case, Intel and other manufacturers are constantly looking for ways to improve the production process. One lengthy process that would often slow down the pro-duction of motherboards with integrated analog I/O functions was FCC certification. The manufacturers developed a way of separating the analog circuitry, for example, modem and analog audio, onto its own card. This allowed the analog circuitry to be separately certified (It was its own expansion card), thus reducing time for FCC certification. This slot and riser card technology was known as the Audio Modem Riser, or AMR. AMR‘s 46-pin slots were once fairly common on many Intel motherboards, but technologies including CNR and Advanced Communications Riser (ACR) are edging out AMR. In addition and despite FCC concerns, integrated components still appear to be enjoying the most success comparatively.
CNR Expansion Slots
The Communications and Networking Riser (CNR) slots that can be found on some Intel motherboards are a replacement for Intel‘s AMR slots. Essentially, these 60- pin slots allow a motherboard manufacturer to implement a motherboard chipset with certain integrated features. Then, if the built-in features of that chipset need to be enhanced (by adding Dolby Digital Surround to a standard sound chipset, for example), a CNR riser card could be added to enhance the onboard capabilities. Additional advantages of CNR over AMR include net-working support, Plug and Play compatibility, support for hardware acceleration (as opposed to CPU control only), and no need to lose a competing PCI slot unless the CNR slot is in use.
TYPES OF ADDON OR DAUGHTER CARDS
Add on cards provide more features to a computer by adding a circuit board connected to the motherboard using PCI (Peripheral Component Interconnect) or PCI Express. Common examples include network cards, video cards, SATA controllers, RAID controllers, audio cards, USB/Firewire cards, etc.
Graphics card
A video card (also called a video adapter, display card, graphics card, graphics board, display adapter or graphics adapter) is an expansion card which generates a feed of output images to a display. A graphics card is a printed circuit board that houses a processor and RAM. It also has an input/output system (BIOS) chip, which stores the card's settings and performs diagnostics on the memory, input and output at startup. A graphics card's processor, called a graphics processing unit (GPU), is similar to a computer's CPU. A GPU, however, is designed specifically for performing the complex mathematical and geometric calculations that are necessary for graphics rendering. Some of the fastest GPUs have more transistors than the average CPU. A GPU produces a lot of heat, so it is usually located under a heat sink or a fan.
In addition to its processing power, a GPU uses special programming to help it analyze and use data. ATI and nVidia produce the vast majority of GPUs on the market, and both companies have developed their own enhancements for GPU performance. To improve image quality, the processors use:
Full scene anti aliasing (FSAA), which smoothes the edges of 3-D objects Anisotropic filtering (AF), which makes images look crisper
As the GPU creates images, it needs somewhere to hold information and completed pictures. It uses the card's RAM for this purpose, storing data about each pixel, its color and its location on the screen. Part of the RAM can also act as a frame buffer, meaning that it holds completed images until it is time to display them. Typically, video RAM operates at very high speeds and is dual ported, meaning that the system can read from it and write to it at the same time.
The RAM connects directly to the digital-to-analog converter, called the DAC. This converter, also called the RAMDAC, translates the image into an analog signal that the monitor can use. Some cards have multiple RAMDACs, which can improve performance and support more than one monitor. Sound card
A sound card (also known as an audio card) is an internal computerexpansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware inside the PC. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment (games) and video projection.
Sound functionality can also be integrated onto the motherboard, using basically the same components as a plug-in card. The best plug-in cards, which use better and more expensive components, can achieve higher quality than integrated sound. The integrated sound system is often still referred to as a "sound card".
Lan Card
A network interface controller (NIC) (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network. Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus; the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard.
Modem A modem (modulator-demodulator) is a device that modulates an analogcarrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from light emitting diodes to radio. The most familiar example is a voice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephone channel. These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data.
There are two type of Modem: -
Internal Modem: -Internal Modem Is Used In-side the Pc.
External Modem: - External Modem Is Used OutsideOfthe Pc.
TV Tuner Card A TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the digital video recorder (DVR) does.The interfaces for TV tuner cards are most commonly either PCIbusexpansion card or the newer PCI Express (PCIe) bus for many modern cards, but PCMCIA, ExpressCard, or USB devices also exist. In addition, some video cards double as TV tuners, notably the ATI All-In-Wonder series. The card contains a tuner and an analog-to-digital converter (collectively known as the analog front end) along with demodulation and interface logic.
Video Editing Card Video editing cards are part of a computer‘s software package and this is usually used for MPEG rendering and also real-time editing of videos. It is mostly used to edit videos of any format acceptable by your machine in real time, meaning that any changes you apply to the video will be immediately applied by the computer.
There are a number of things that a video editing card can: a) Basic video editing facilities b) Video duplication c) Conversion between various video formats d) Converting still images into video e) Archiving and compacting the video
SCSI Card
SCSI (pronounced scuzzy) is short for Small Computer System Interface, and the SCSI card controls various SCSI devices. SCSI devices might be hard drives, optical drives, scanners or tape drives.
A SCSI card is inserted into a PCI slot inside the computer. SCSI is a competing technology to the more standard IDE (Integrated Drive Electronics). Most hard disks are IDE, but the IDE controller card is integrated into the motherboard. If SCSI components are desired, a SCSI card is required.
There are various versions of the SCSI card that feature different connectors as the technology has evolved.
25-pin card controls original SCSI devices 50-pin card controls Narrow (8-bit) SCSI-2, FastSCSI, and Ultra SCSI devices 68-pin card controls Wide (16-bit) Ultra-Wide, Ultra2, Ultra 160, and Ultra 320 devices
Many people prefer SCSI to standard IDE as SCSI technology is much faster. SCSI drives are popular in servers and among power users. A SCSI card has its own processing chip and does not need to rely on the CPU (Central Processing Unit). The trade-off is that SCSI devices are more expensive than IDE devices.
TYPES OF PORTS
DIN- DUTCH INDUSTRIAL NORMS
A DIN connector is a connector that was originally standardized by the Deutsches Institut für Normung (DIN), the German national standards organization.The first two generations of PC keyboards (PC and AT keyboards) used a 5- pin DIN connector.The smaller 6-pin Mini-DIN connector replaced the 5-pin "AT" connector, and 6-pin to 5-pin adapters were commonly used to attach a new keyboard to an old PC. The 6-pin Mini-DIN also replaced the serial port for mouse.
PS/2 PORT
The port was introduced with IBM's Personal System/2 computer in 1987 (which was abbreviated "PS/2").The PS/2 port has six pins and is roughly circular in shape. Since each PS/2 port is designed to accept a specific input, the keyboard and mouse connections are typically color-coded.
USB Port
Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power. It has become commonplace on other devices, such as smartphones, PDAs and video game consoles. USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.
USB Version
USB 1 (Full Speed) Released in January 1996, USB 1 specified data rates of 1.5 Mb/s (Low- Bandwidth) and 12 Mb/s (Full-Bandwidth). It did not allow for extension cables or pass-through monitors (due to timing and power limitations).
USB 2.0 (High Speed) USB 2.0 Released in April 2000. Added higher maximum signaling rate of 480 Mbit/s (effective throughput up to 35 MB/s or 280 Mbit/s) (now called "Hi-Speed").
USB 3.0 (Super Speed) USB 3.0 was released in November 2008. The standard defines a new "SuperSpeed" mode with a signalling speed of 5 Gbit/s and a usable data rate of up to 4 Gbit/s. USB 3.0 reduces the time required for data transmission, therefore reducing power consumption, and it is backward compatible with USB 2.0.
LPT Port The parallel port interface was originally known as the LPT port (Line Print Terminal, Local Print Terminal, or Line Printer) which is use for connecting an external device such as a printer. It has 25 number of terminal.
IEEE 1394 Port The IEEE 1394 interface is a serial businterface standard for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple, who called it FireWire.A single 1394 port can be used to connect up 63 external devices. In addition to its high speed, 1394 also supports isochronousdata-- delivering data at a guaranteed rate. This makes it ideal for devices that need to transfer high levels of data in real-time, such as video devices.
Lan Port Alternatively referred to as an Ethernet port, network connection, and network port, the LAN port is a port connection that allows a computer to connect to a network using a wired connection.An Ethernet port looks much like a regular phone jack, but it is slightly wider. It has 8 number of pin. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem.
Serial Port This port is also known as com port or communication port. A socket on a computer used to connect a modem, data acquisition terminal or other device via a serial interface (one data bit following the other). Serial ports provide very slow speeds and have been superseded by USB and other faster interfaces for peripheral connections to desktop computers. Although still widely used in data acquisition, the serial port is no longer found on new computers. Earlier PCs used the port for the mouse, and earlier Macintoshes used it to attach a printer.
VGA Port Stands for "Video Graphics Array" It is the standard monitor or display interface used in most PCs. Therefore, if a monitor is VGA-compatible, it should work with most new computers. The VGA standard was originally developed by IBM in 1987 and allowed for a display resolution of 640x480 pixels. The most common is Super VGA (SVGA), which allows for resolutions greater than 640x480, such as 800x600 or 1024x768. A standard VGA connection has 15 pins and is shaped like a trapezoid.
DVI Port Stands for "Digital Video Interface" DVI is a video connection standard created by the Digital Display Working Group (DDWG). Most DVI ports support both analog and digital displays. If the display is analog, the DVI connection converts the digital signal to an analog signal. If the display is digital, no conversion is necessary. There are three types of DVI connections: 1) DVI-A (for analog) 2) DVI-D (for digital) 3) DVI-I (integrated, for both analog and digital)
HDMI Port HDMI (High Definition Multimedia Interface) is a specification that combines video and audio into a single digital interface for use with digital versatile disc (DVD) players, digital television (DTV) players, set-top boxes, and other audiovisual devices. The basis for HDMI is High Bandwidth Digital Content Protection (HDCP) and the core technology of Digital Visual Interface (DVI). HDCP is an Intel specification used to protect digital content transmitted and received by DVI-compliant displays. HDMI supports standard, enhanced, or high-definition video plus standard to multi-channel surround-sound audio. HDMI benefits include uncompressed digital video, a bandwidth of up to 5 gigabytes per second, one connector instead of several cables and connectors, and communication between the video source and the DTV. It has 20 numbers of pins.
SCSI Port
Small Computer System Interface (SCSI) is parallel interfacestandard used by Apple Macintosh computers, PCs, and many UNIXsystems for connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners and CDdrives, although not all controllers can handle all devices. Nearly all Apple Macintosh computers, excluding only the earliest Macs and the recent iMac, come with a SCSI port for attaching devices such as disk drives and printers.
SCSI interfaces provide for faster data transmission rates (up to 80 megabytes per second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/Obus rather than simply an interface.
IDE Port
IDE also stands for integrated development environment. IDE (Integrated Drive Electronics) is a standard port used for connecting computer's disk storage devices with motherboard's data paths or bus. Most computers sold today use an enhanced version of IDE called Enhanced Integrated Drive Electronics (EIDE). In today's computers, the IDE controller is often built into the motherboard. IDE was adopted as a standard by American National Standards Institute (ANSI) in November, 1990. The ANSI name for IDE is Advanced Technology Attachment (ATA). It has 39-40 numbers of pin.
Connectors Connectors Are Used to ConnectDevices tothe Computer motherboard.The Connectors Having Holes Are Called Parallel/Female Connectors &The Connector Having Pins Are Called Serial/MaleConnectors. According To Interface,there are Various Types of Connectors on the Mother Board.
TYPES OF CONNECTORS
PS/2 CONNECTOR DIN CONNECTOR USB CONNECTOR LPT CONNECTOR VGA CONNECTOR FLOPPY CONNECTOR IDE CONNECTOR COM CONNECTOR MIDI CONNECTOR SCSI CONNECTOR
Things to consider before buying a new motherboard Before you go about buying a new motherboard, make sure it's something that needs to be done. If you're upgrading it for more functionality or better performance, that's fine, but if you're replacing it because you think it's broken or causing problems, exhausts all other troubleshooting options before replacing the board. Motherboards can be expensive, and it might not even be the real problem.
If you're replacing your motherboard due to a problem, your best bet is to replace it with the exact same board. That way, you know you won't have compatibility issues with any of your other devices or software.
If you're upgrading your motherboard or you want to replace it with a different board, make sure that the new board is compatible with your CPU, RAM all of your expansion cards, and your hard drive. For everything but the CPU, it's just a matter of making sure the motherboard has the right ports and can handle the RAM you currently have installed. Check for compatibility with the type of RAM you have (such as DDR2), its speed, and its size. For the CPU, you need to make sure the new board has the correct slot or socket and is capable of outputting the voltage your CPU requires. You also have to choose a motherboard that will fit in your current case (unless you plan on replacing the case as well).
Most of your current motherboard's specifications can be found either in your motherboard book (if you have one) or in your computer's user manual. If you don't have a computer manual, you can usually download one from the manufacturer's website, or call them to request one.
Another thing to consider before buying a new motherboard is your CPU. Technology develops very quickly, and the CPU you have might already be outdated. If you're upgrading your motherboard for better performance, you might want to also think about buying a new, more powerful CPU. Purchasing a new CPU and motherboard at the same time will give you more flexibility with your options.
Motherboard Troubleshooting
A.)GENERAL TESTING TIPS. Ideally, troubleshooting is best accomplished with duplicate parts from a used computer enabling "test" swapping of peripheral devices/cards/chips/cables. In general, it is best to troubleshoot on systems that have been leaned-out. Remove unnecessary peripherals (soundcard, modem, harddisk, etc.) to check the unworking device in as much isolation as possible. Also, when swapping devices, don't forget the power supply. Power incompetency (watts and volts) can cause intermittent problems at all levels, but especially with UARTS and HD's. Inspect the motherboard for loose components. A loose or missing CPU, BIOS chip, Crystal Oscillator, or Chipset chip will cause the motherboard not to function. Also check for loose or missing jumper caps, missing or loose memory chips (cache and SIMM's or DIMM's). To possibly save you hours of frustration I will mention this here, check the BIOS Setup settings. 60% of the time this is the cause of many system failures. A quick fix is to restore the BIOS Defaults. Next, eliminate the possibility of interference by a bad or improperly set up I/O card by removing all cards except the video adapter. The system should at least power up and wait for a drive time-out. Insert the cards back into the system one at a time until the problem happens again. When the system does nothing, the problem will be with the last expansion card that was put in. B.)RESETTING CMOS. Did you recently 'flash' your computers BIOS, and needed to change a jumper to do so? Perhaps you left the jumper in the 'flash' position which could cause the CMOS to be erased. If you require the CMOS Reset and don't have the proper jumper settings try these methods: Our Help Desk receives so many requests on Clearing BIOS/CMOS Passwords that we've put together a standard text outlining the various solutions.
C.)NO POWER. Switching power supplies (the most common used PC's), cannot be adequately field-tested with V/OHM meters. Remember: for most switching power supplies to work, a FLOPPY and at least 1 meg of memory must be present on the motherboard. If the necessary components are present on the motherboard and there is no power: 1) Check the power cable to the wall and that the wall socket is working. (You'd be surprised!) 2) Swap power supply with one that is known to work. 3) If the system still doesn't work, check for fuses on the motherboard. If there are none, you must replace the motherboard.
D.)PERIPHERAL WON'T WORK. Peripherals are any devices that are connected to the motherboard, including I/O boards, RS232/UART devices (including mice and modems), floppies and fixed-disks, video cards, etc. On modern boards, many peripherals are integrated into the motherboard, meaning, if one peripheral fails, effectually the motherboard has to be replaced.* On older boards, peripherals were added via daughter boards. *some MB CMOS's allow for disabling on-board devices, which may be an option for not replacing the motherboard -- though, in practicality, some peripheral boards can cost as much, if not more, than the motherboard. Also, failure of on-board devices may signal a cascading failure to other components. 1. New peripheral? a) Check the MB BIOS documentation/setup to ensure that the BIOS supports the device and that the MB is correctly configured for the device. (Note>> when in doubt, reset CMOS to DEFAULT VALUES. These are ) (optimized for the most generalized settings that avoid some of) (the conflicts that result from improper 'tweaking'. ) b) Check cable attachments & orientation (don't just look, reattach!) c) If that doesn't work, double-check jumper/PnP (including software and/or MB BIOS set) settings on the device. d) If that doesn't work, try another peripheral of same brand & model that is known to work. e) If the swap peripheral works, the original peripheral is most likely the problem. (You can verify this by testing the non-working peripheral on a test MB of the same make & bios.) f) If the swap periphal doesn't on the MB, verify the functionality of the first peripheral on a test machine. If the first peripheral works on another machine AND IF the set-up of the motherboard BIOS is verified AND IF all potentially conflicting peripherals have been removed OR verified to not be in conflict, the motherboard is suspect. (However, see #D below.) g) At this point, recheck MB or BIOS documentation to see if there are known bugs with the peripheral AND to verify any MB or peripheral jumper settings that are necessary for the particular peripheral to work. Also, try a different peripheral of the same kind but a different make to see if it works. If it does not, swap the motherboard. (However, see #D below.)
2. Peripheral that worked before? a) If the hood has been opened (or even if it has not), check the orientation and/or seating of the cables. Cables sometimes 'shake' loose or are accidentally pulled out by end-users, who then misalign or do not reattach them. b) If that doesn't work, try the peripheral in another machine of the same make & bios that is known to work. If the peripheral still doesn't work, the peripheral is most likely the problem. (This can be verified by swapping-in a working peripheral of the same make and model AND that is configured the same as the one that is not working. If it works, then the first peripheral is the problem.) c) If the peripheral works on another machine, double-check other peripherals and/or potential conflicts on the MB, including the power supply. If none can be found, suspect the MB. d) At this point, recheck MB or BIOS documentation to see if there are known bugs with the peripheral AND to verify any jumper settings that might be necessary for the particular peripheral. Also, try another peripheral of the same kind but a different make to see if it works. If not, swap the motherboard!
E.)OTHER INDICATIONS OF A PROBLEM MOTHERBOARD. 1. CLOCK that won't keep correct time. >>Be sure to check/change the battery. 2. CMOS that won't hold configuration information. >>Again, check/change the battery. Note about batteries and CMOS: in theory, CMOS should retain configuration information even if the system battery is removed or dies. In practice, some systems rely on the battery to hold this information. On these systems, a machine that is not powered-up for a week or two may report improper BIOS configuration. To check this kind of system, change the battery, power-up and run the system for several hours. If the CMOS is working, the information should be retained with the system off for more than 24 hours.
F.)BAD MOTHERBOARD OR OBSOLETE BIOS? 1. If the motherboard cannot configure to a particular peripheral, don't automatically assume a bad motherboard, even if the peripheral checks out on another machine -- especially if the other machine has a different BIOS revision. Check with the board manufacturer to see if a BIOS upgrade is available. Many BIOS upgrades can be made right on the MB with a FLASH RAM program provided by the board maker. See our BIOS page for more information.
Processor
CPU is the abbreviation for central processing unit. Sometimes referred to simply as the central processor, but more commonly called processor, the CPU is the brains of the computer where most calculations take place. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor.
The CPU itself is an internal component of the computer. Modern CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard.
Each motherboard will support only a specific type (or range) of CPU, so you must check the motherboard manufacturer's specifications before attempting to replace or upgrade a CPU in your computer. Modern CPUs also have an attached heat sink and small fan that go directly on top of the CPU to help dissipate heat.
Two typical components of a CPU are the following:
The arithmetic logic unit(ALU), which performs arithmetic and logical operations. The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.
PC Processor Evolution
Since the first PC came out in 1981, PC processor evolution has concentrated on four main areas:
Increasing the transistor count and density Increasing the clock cycling speeds Increasing the size of internal registers (bits) Increasing the number of cores in a single chip
16-Bit to 64-Bit Architecture Evolution
The first major change in processor architecture was the move from the 16-bit internal architecture of the 286 and earlier processors to the 32-bit internal architecture of the 386 and later chips, which Intel calls IA-32 (Intel Architecture, 32-bit). Intel‘s 32-bit architecture dates to 1985. It took a full 10 years for both a partial 32-bit mainstream OS (Windows 95) as well as a full 32-bit OS requiring 32-bit driver (Windows NT) to surface, and it took another 6 years for the mainstream to shift to a fully 32-bit environment for the OS and drivers (Windows XP). That‘s a total of 16 years from the release of 32-bit computing hardware to the full adoption of 32-bit computing in the mainstream with supporting software. I‘m sure you can appreciate that 16 years is a lifetime in technology.
Now we are near the end of another major architectural jump, as Intel, AMD, and Microsoft have almostcompletely shifted from 32-bit to 64-bit architectures. In 2001, Intel had introduced the IA-64 (Intel Architecture, 64-bit) in the form of the Itanium and Itanium 2 processors, but this standard was something completely new and not an extension of the existing 32-bit technology. IA-64 was announced in 1994 as a CPU development project with Intel and HP (code-named Merced), and the first technical details were made available in October 1997.
The fact that the IA-64 architecture is not an extension of IA-32 but is instead a new and completelydifferent architecture was fine for non-PC environments such as servers (for which IA-64 was designed), but the PC market has always hinged on backward compatibility. Even though emulating IA-32 within IA-64 is possible, such emulation and support is slow.
With the door now open, AMD seized this opportunity to develop 64-bit extensions to IA-32, which it callsAMD64 (originally known as x86-64). Intel eventually released its own set of 64-bit extensions, which it calls EM64T or IA-32e mode. As it turns out, the Intel extensions are almost identical to the AMD extensions, meaning they are software compatible. It seems for the first time that Intel has unarguably followed AMD‘s lead in the development of PC architecture. However, AMD and Intel‘s 64-bit processor could only run in 32-bit mode on existing operating systems. To make 64-bit computing a reality, 64-bit OSs and 64-bit drivers are also needed. Microsoft began providing trial versions of Windows XP Professional x64 Edition (which supports AMD64 and EM64T) in April 2005, but it wasn‘t until the release of Windows Vista x64 in 2007 that 64-bit computing would begin to go mainstream. Initially, the lack of 64-bit drivers was a problem, but by the release of Windows 7 x64 in 2009, most device manufacturers were providing both 32-bit and 64-bit drivers for virtually all new devices. Linux is also available in 64-bit versions, making the move to 64-bit computing possible for non-Windows environments as well.
Another important development is the introduction of multicore processors from both Intel and AMD. Current multicore desktop processors have up to six full CPU cores operating off of one CPU package in essence enabling a single processor to perform the work of multiple processors. Although multicore processors don‘t make games that use single execution threads play faster, multicore processors, like multiple single-core processors, split up the workload caused by running multiple applications at the same time. If you‘ve ever tried to scan for malware while simultaneously checking email or running another application, you‘ve probably seen how running multiple applications can bring even the fastest processor to its knees. With multicore processors available from both Intel and AMD, your ability to get more work done in less time by multitasking is greatly enhanced. Multicore processors also support 64-bit extensions, enabling you to enjoy both multicore and 64-bit computing advantages.
PCs have certainly come a long way. The original 8088 processor used in the first PC contained 29,000 transistors and ran at 4.77MHz. Compare that to today‘s chips: The AMD Phenom II x6 has an estimated 904 million transistors and runs at up to 3.3GHz or faster, and the six-core Intel Core i7 models have around 1.17 million transistors and run at up to 3.4GHz or faster. As multicore processors with large integrated caches continue to be used in designs, look for transistor counts and real-world performance to continue to increase well beyond a billion transistors. And the progress won‘t stop there, because according to Moore‘s Law, processing speed and transistor counts are doubling every 1.5–2 years.
Processor Specifications Many confusing specifications often are quoted in discussions of processors. The following sections discuss some of these specifications, including the data bus, address bus, and speed. The next section includes a table that lists the specifications of virtually all PC processors. Processors can be identified by two main parameters: how wide they are and how fast they are. The speed of a processor is a fairly simple concept. Speed is counted in megahertz (MHz) and gigahertz (GHz), which means millions and billions, respectively, of cycles per second—and faster is better! The width of a processor is a little more complicated to discuss because three main specifications in a processor are expressed in width:
Data (I/O) bus (also called FSB or front side bus) Address bus Internal registers
Data I/O Bus Two of the more important features of a processor are the speed and width of its external data bus. These define the rate at which data can be moved into or out of the processor. Data in a computer is sent as digital information in which certain voltages or voltage transitions occurring within specific time intervals represent data as 1s and 0s. You can increase the amount of data being sent (called bandwidth) by increasing either the cycling time or the number of bits being sent at a time, or both. Over the years, processor data buses have gone from 8 bits wide to 64 bitswide. The more wires you have,
the more individual bits you can send in the same interval. All modern processors from the original Pentium and Athlon through the latest Core 2, Athlon 64 X2, and even the Itanium and Itanium 2 have a 64-bit (8-byte)-wide data bus. Therefore, they can transfer 64 bits of data at a time to and from the motherboard chipset or system memory.The wider the bus, the more data that can be processed per unit of time, and hence the more work that can be performed. Internal registers in the CPU might be only 32 bits wide, but with a 64-bit system bus, two separate pipelines can receive information simultaneously.
Address Bus The address bus is the set of wires that carry the addressing information used to describe the memory location to which the data is being sent or from which the data is being retrieved. As with the data bus, each wire in an address bus carries a single bit of information. This single bit is a single digit in the address. The more wires (digits) used in calculating these addresses, the greater the total number of address locations. The size (or width) of the address bus indicates the maximum amount of RAM a chip can address.
Internal Registers (Internal Data Bus) The size of the internal registers indicates how much information the processor can operate on at one time and how it moves data around internally within the chip. This is sometimes also referred to as the internal data bus. A register is a holding cell within the processor; for example, the processor canadd numbers in two different registers, storing the result in a third register. The register size determines the size of data on which the processor can operate. The register size also describes the type of software or commands and instructions a chip can run. That is, processors with 32-bit internal registers can run 32-bit instructions that are processing 32-bit chunks of data, but processors with 16-bit registers can‘t. Processors from the 386 to the Pentium 4 use 32-bit internal registers and can run essentially the same 32-bit OSs and software. The Core 2, Athlon 64, and newer processors have both 32-bit and 64-bit internal registers, which can run existing 32-bit OSs and applications as well as newer 64-bit versions.
Processor Modes All Intel and Intel-compatible processors from the 386 on up can run in several modes. Processor modes refer to the various operating environments and affect the instructions and capabilities of the chip. The processor mode controls how the processor sees and manages the system memory and the tasks that use it.
Summarizes the processor modes and submodes.
Processor Modes
OS Memory Default Register Mode Submode Required Software Address Size Operand Size Width
Real — 16-bit 16-bit 24-bit 16-bit 16-bit
IA-32 Protected 32-bit 32-bit 32-bit 32-bit 32/16-bit
Virtual real 32-bit 16-bit 24-bit 16-bit 16-bit
IA-32e 64-bit 64-bit 64-bit 64-bit 32-bit 64-bit Compatibility 64-bit 32-bit 32-bit 32-bit 32/16-bit
IA-32e (64-bit extension mode) is also called x64, AMD64, x86-64, or EM64T
Real Mode Real mode is sometimes called 8086 mode because it is based on the 8086 and 8088 processors. Theoriginal IBM PC included an 8088 processor that could execute 16-bit instructions using 16-bit internal registers and could address only 1MB of memory using 20 address lines. All original PC software was created to work with this chip and was designed around the 16-bit instruction set and 1MB memory model. For example, DOS and all DOS software, Windows 1.x through 3.x, and all Windows 1.x through 3.x applications are written using 16-bit instructions. These 16-bit OSs and applications are designed to run on an original 8088 processor.
IA-32 Mode (32-Bit) Then came the 386, which was the PC industry‘s first 32-bit processor. This chip could run an entirelynew 32-bit instruction set. To take full advantage of the 32-bit instruction set, a 32-bit OS and a 32-bit application were required. This new 32-bit mode was referred to as protected mode, which alludes to the fact that software programs running in that mode are protected from overwriting one another in memory. Such protection makes the system much more crash-proof because an errant program can‘t easily damage other programs or the OS. In addition, a crashed program can be terminated while the rest of the system continues to run unaffected.
When a 386 or later processor is running DOS (real mode), it acts like a ―Turbo 8088,‖ which means the processor has the advantage of speed in running any 16-bit programs; it otherwise can use only the 16-bit instructions and access memory within the same 1MB memory map of the original 8088. Therefore, if you have a system with a current 32-bit or 64-bit processor running Windows 3.x or DOS, you are effectively using only the first megabyte of memory, leaving all the other RAM largely unused!
Windows XP was the first true 32-bit OS that became a true mainstream product, and that is primarily because Microsoft coerced us in that direction with Windows 9x/Me (which are mixed 16-bit/32-bit systems). Windows 3.x was the last 16-bit OS, which some did not really consider a complete OS because it ran on top of DOS.
IA-32 Virtual Real Mode The key to the backward compatibility of the Windows 32-bit environment is the third mode in the processor: virtual real mode. Virtual real is essentially a virtual real mode 16-bit environment that runs inside 32-bit protected mode. When you run a DOS prompt window inside Windows, you have created a virtual real mode session. Because protected mode enables true multitasking, you can actually have several real mode sessions running, each with its own software running on a virtual PC. These can all run simultaneously, even while other 32-bit applications are running.
Virtual real mode is used when you use a DOS window to run a DOS or Windows 3.x 16-bit program. When you start a DOS application, Windows creates a virtual DOS machine under which it can run. One interesting thing to note is that all Intel and Intel-compatible (such as AMD and VIA/Cyrix)processors power up in real mode. If you load a 32-bit OS, it automatically switches the processor into32-bit mode and takes control from there.
IA-32e 64-Bit Extension Mode (x64, AMD64, x86-64, EM64T) 64-bit extension mode is an enhancement to the IA-32 architecture originally designed by AMD and later adopted by Intel. In 2003, AMD introduced the first 64-bit processor for x86-compatible desktop computers—theAthlon 64— followed by its first 64-bit server processor, the Opteron. In 2004, Intel introduced a series of 64-bit-enabled versions of its Pentium 4 desktop processor. The years that followed saw both companies introducing more and more processors with 64-bit capabilities. Processors with 64-bit extension technology can run in real (8086) mode, IA-32 mode, or IA-32e mode. IA-32 mode enables the processor to run in protected mode and virtual real mode. IA-32e mode allows the processor to run in 64-bit mode and compatibility mode, which means you can run both 64-bit and 32-bit applications simultaneously.
IA-32e mode includes two submodes:
64-bit mode—Enables a 64-bit OS to run 64-bit applications Compatibility mode—Enables a 64-bit OS to run most existing 32-bit software
IA-32e 64-bit mode is enabled by loading a 64-bit OS and is used by 64-bit applications. In the 64-bit submode, the following new features are available:
64-bit linear memory addressing Physical memory support beyond 4GB (limited by the specific processor) Eight new general-purpose registers (GPRs) Eight new registers for streaming SIMD extensions (MMX, SSE, SSE2, and SSE3) 64-bit-wide GPRs and instruction pointers
Comparing Processor Performance A common misunderstanding about processors is their different speed ratings. This section covers processor speed in general and then provides more specific information about Intel, AMD, and VIA/Cyrix processors. A computer system‘s clock speed is measured as a frequency, usually expressed as a number of cycles per second. A crystal oscillator controls clock speeds using a sliver of quartz sometimes housed in what looks like a small tin container. Newer systems include the oscillator circuitry in the motherboard chipset, so it might not be a visible separate component on newer boards. As voltage is applied to the quartz, it begins to vibrate (oscillate) at a harmonic rate dictated by the shape and size of the crystal (sliver). The oscillations emanate from the crystal in the form of a current that alternates at the harmonic rate of the crystal. This alternating current is the clock signal that forms thetime base on which the computer operates. A typical computer system runs millions or billions of these cycles per second, so speed is measured in megahertz or gigahertz. (One hertz is equal to one cycle per second.) An alternating current signal is like a sine wave, with the time between the peaks of each wave defining the frequency.
The hertz was named for the German physicist Heinrich Rudolf Hertz. In 1885, Hertz confirmed the electromagnetic theory, which states that light is a form of electromagnetic radiation and is propagated as waves.
A single cycle is the smallest element of time for the processor. Every action requires at least one cycle and usually multiple cycles. To transfer data to and from memory, for example, a modern processor such as the Pentium 4 needs a minimum of three cycles to set up the first memory transfer and then only a single cycle per transfer for the next three to six consecutive transfers. The extra cycles on the first transfer typically are called wait states. A wait state is a clock tick in which nothing happens. This ensures that the processor isn‘t getting ahead of the rest of the computer. The time required to execute instructions also varies:
8086 and 8088—The original 8086 and 8088 processors take an average of 12 cycles to execute a single instruction. 286 and 386—The 286 and 386 processors improve this rate to about 4.5 cycles per instruction. 486—The 486 and most other fourth-generation Intel-compatible processors, such as the AMD 5x86, drop the rate further, to about 2 cycles per instruction. Pentium/K6—The Pentium architecture and other fifth-generation Intel-compatible processors, such as those from AMD and Cyrix, include twin instruction pipelines and other improvements that provide for operation at one or two instructions per cycle. P6/P7 and newer—Sixth-, seventh-, and newer-generation processors can execute as many as three or more instructions per cycle, with multiples of that possible on multicore processors.
Different instruction execution times (in cycles) make comparing systems based purely on clock speed or number of cycles per second difficult. How can two processors that run at the same clock rate perform differently, with one running ―faster‖ than the other? The answer is simple: efficiency.
The main reason the 486 is considered fast relative to the 386 is that it executes twice as many instructions in the same number of cycles. The same thing is true for a Pentium; it executes about twice as many instructions in a given number of cycles as a 486. Therefore, given the same clock speed, a Pentium is twice as fast as a 486, and consequently a 133MHz 486 class processor (such as the AMD 5x86-133) is not even as fast as a 75MHz Pentium! That is because Pentium megahertz are ―worth‖ about double what 486 megahertz are worth in terms of instructions completed per cycle. The Pentium II and III are about 50% faster than an equivalent Pentium at a given clock speed because they can execute about that many more instructions in the same number of cycles.
Unfortunately, after the Pentium III, it becomes much more difficult to compare processors on clock speed alone. This is because the different internal architectures make some processors more efficient than others, but these same efficiency differences result in circuitry that is capable of running at different maximum speeds. The less efficient the circuit, the higher the clock speed it can attain, and vice versa. A deeper pipeline effectively breaks down instructions into smaller microsteps, which allows overall higher clock rates to be achieved using the same silicon technology. However, this also means that overall fewer instructions can be executed in a single cycle as compared to processors with shorter pipelines. This is because, if a branch prediction or speculative execution step fails (which happens fairly frequently inside the processor as it attempts to line up instructions in advance), the entire pipeline has to be flushed and refilled.
Cache Memory As processor core speeds increased, memory speeds could not keep up. How could you run a processor faster than the memory from which you fed it without having performance suffer terribly? The answer was cache. In its simplest terms, cache memory is a high-speed memory buffer that temporarily stores data the processor needs, allowing the processor to retrieve that data faster than if it came from main memory. But there is one additional feature of a cache over a simple buffer, and that is intelligence. A cache is a buffer with a brain. A buffer holds random data, usually on a first-in, first-out basis or a first-in, last-out basis. A cache, on the other hand, holds the data the processor is most likely to need in advance of it actually being needed. This enables the processor to continue working at either full speed or close to it without having to wait for the data to be retrieved from slower main memory. Cache memory is usually made up of static RAM (SRAM) memory integrated into the processor die, although older systems with cache also used chips installed on the motherboard. Cache is even more important in modern processors because it is often the only memory in the entire system that can truly keep up with the chip. Most modern processors are clock multiplied, which means they are running at a speed that is really a multiple of the motherboard into which they are plugged. The only types of memory matching the full speed of the processor are the L1, L2, and L3 caches built into the processor core. For the majority of desktop systems, there are two levels of processor/memory cache used in a modern PC: Level 1 (L1) and Level 2 (L2). An increasing number of high-performance processors also have Level 3 cache.
Internal Level 1 Cache All modern processors starting with the 486 family include an integrated L1 cache and controller. The integrated L1 cache size varies from processor to processor, starting at 8KB for the original 486DX and now up to 128KB or more in the latest processors. Multi-core processors include separate L1 caches for each processor core. Also, L1 cache is divided into equal amounts for instructions and data.If the data that the processor wants is already in L1 cache, the CPU does not have to wait. If the data is not in the cache, the CPU must fetch it from the Level 2 or Level 3 cache or (in less sophisticated system designs) from the system bus—meaning main memory directly.
Level 2 Cache To mitigate the dramatic slowdown every time an L1 cache miss occurs, a secondary (L2) cache is employed.All modern processors have integrated L2 cache that runs at the same speed as the processor core, which is also the same speed as the L1 cache.
Level 3 Cache Some processors, primarily those designed for high-performance desktop operation or enterprise-level servers, contain a third level of cache known as L3 cache. In the past, relatively few processors had L3 cache, but it is becoming more and more common in newer and faster multicore processors such as the Intel Core i7 and AMD Phenom II processors.L3 cache proves especially useful in multicore processors, where the L3 is generally shared among allthe cores. Both Intel and AMD use L3 cache in most of their current processors because of the benefits tomulticore designs.
Processor Features As new processors are introduced, new features are continually added to their architectures to improve everything from performance in specific types of applications to the reliability of the CPU as a whole.
System Management Mode (SMM) Spurred on initially by the need for more robust power management capabilities in mobile computers, Intel and AMD began adding System Management Mode (SMM) to its processors during the early 1990s. SMM is a special- purpose operating mode provided for handling low-level system power managementand hardware control functions. SMM offers an isolated software environment that is transparent to the OS or applications software and is intended for use by system BIOS or low-level driver code.
Superscalar Execution The fifth-generation Pentium and newer processors feature multiple internal instruction execution pipelines, which enable them to execute multiple instructions at the same time. The 486 and all preceding chips can perform only a single instruction at a time. Intel calls the capability to execute more than one instruction at a time superscalar technology. Superscalar architecture was initially associated with high-output reduced instruction set computer (RISC) chips. A RISC chip has a less complicated instruction set with fewer and simpler instructions.
MMX Technology MMX technology was originally named for multimedia extensions, or matrix math extensions, dependingon whom you ask. Intel officially states that it is actually not an abbreviation and stands for nothing other than the letters MMX (not being an abbreviation was apparently required so that the letters could be trademarked); however, the internal origins are probably one of the preceding. MMX technology was introduced in the later fifth-generation Pentium processors as a kind of add-on that improves video compression/decompression, image manipulation, encryption, and I/O processing— all of which are used in a variety of today‘s software.
MMX consists of two main processor architectural improvements. The first is basic: All MMX chips have a larger internal L1 cache than their non-MMX counterparts. This improves the performance of any and all software running on the chip, regardless of whether it actually uses the MMX-specificinstructions.
SSE In February 1999, Intel introduced the Pentium III processor and included in that processor an update to MMX called Streaming SIMD Extensions (SSE). These were also called Katmai New Instructions (KNI) up until their debut because they were originally included on the Katmai processor, which was the code name for the Pentium III. The Celeron 533A and faster Celeron processors based on the Pentium III core also support SSE instructions. The earlier Pentium II and Celeron 533 and lower (based on the Pentium II core) do not support SSE.
3DNow! 3DNow! technology was originally introduced as AMD‘s alternative to the SSE instructions in the Intel processors. It included three generations: 3D Now!, Enhanced 3D Now!, and Professional 3D Now! (Which added full support for SSE)? AMD announced in August 2010 that it was dropping support for 3D Now!-specific instructions in upcoming processors.
Dynamic Execution First used in the P6 (or sixth-generation) processors, dynamic execution enables the processor to execute more instructions in parallel, so tasks are completed more quickly. This technology innovation is composed of three main elements:
Multiple branch prediction—Predicts the flow of the program through several branches. Dataflow analysis—Schedules instructions to be executed when ready, independent of their rder in the original program. Speculative execution—Increases the rate of execution by looking ahead of the program counter and executing instructions that are likely to be necessary.
Dual Independent Bus Architecture The Dual Independent Bus (DIB) architecture was first implemented in the sixth-generation processors from Intel and AMD. DIB was created to improve processor bus bandwidth and performance. Having two (dual) independent data I/O buses enables the processor to access data from either of its buses simultaneously and in parallel, rather than in a singular sequential manner (as in a single-bus system). The main (often called front-side) processor bus is the interface between the processor and the motherboard or chipset. The second (back-side) bus in a processor with DIB is used for the L2 cache, enabling it to run at much greater speeds than if it were to share the main processor bus. Two buses make up the DIB architecture: the L2 cache bus and the main CPU bus, often called FSB (front-side bus). The P6 class processors, from the Pentium Pro to the Core 2, as well as Athlon 64 processors can use both buses simultaneously, eliminating a bottleneck there. The dual bus architecture enables the L2 cache of the newer processors to run at full speed inside the processor core on an independent bus, leaving the main CPU bus (FSB) to handle normal data flowing in and out of the chip. The two buses run at different speeds. The front-side bus or main CPU bus is coupled to the speed of the motherboard, whereas the back-side or L2 cache bus is coupled to the speed of theprocessor core. As the frequency of processors increases, so does the speed of the L2 cache.
HT Technology Intel‘s HT Technology allows a single processor or processor core to handle two independent sets of instructions at the same time. In essence, HT Technology converts a single physical processor core into two virtual processors. HT Technology was introduced on Xeon workstation-class processors with a 533MHz system bus in March 2002. It found its way into standard desktop PC processors starting with the Pentium 4 3.06GHz processor in November 2002. HT Technology predates multicore processors, so processors that have multiple physical cores, such as the Core 2 and Core i Series, may or may not support this technology depending on the specific processor version. A quad-core processor that supports HT Technology (like the Core i Series) would appear as an 8-core processor to the OS; Intel‘s Core i7-990x has six cores and supports up to 12 threads.
Multicore Technology HT Technology simulates two processors in a single physical core. If multiple simulated processors are good, having two or more real processors is a lot better. A multicore processor, as the name implies, actually contains two or more processor cores in a single processor package. From outward appearances, it still looks like a single processor (and is considered as such for Windows licensing purposes), but inside there can be two, three, four, or even more processor cores. A multicore processor provides virtually all the advantages of having multiple separate physical processors, all at a much lower cost.
Throttling CPU throttling, or clamping, is the process of controlling how much CPU time is spent on an application. By controlling how individual applications use the CPU, all applications are treated more fairly. The concept of application fairness becomes a particular issue in server environments, where each application could represent the efforts of a different user. Thus, fairness to applications becomes fairness to users, the real customers. Clients of today‘s terminal servers benefit from CPU throttling.
Overclocking Overclocking your CPU offers increased performance, on par with a processor designed to operate at the overclocked speed. However, unlike with the processor designedto run that fast, you must make special arrangements to ensure that an overclocked CPU does not destroy itself from the increased heat levels. An advanced cooling mechanism, such as liquid cooling, might be necessary to avoid losing the processor and other components.
Voltage Regulator Module The voltage regulator module (VRM) is the circuitry that sends a standard voltage level to the portion of the processor that is able to send a signal back to the VRM concerning the voltage level the CPU needs. After receiving the signal, the VRM truly regulates the voltage to steadily provide the requested voltage.
Processor packaging A raw processor chip is very small and fragile, and for this reason it is extremely difficult to make connections to it and easy to damage it. With one exception, chips are not placed into motherboards in their raw form, but rather after having been packaged in a material that protects them, allows them to dissipate heat properly, and has connectors of a standard size and shape. This allows motherboards to be made in a more standardized fashion without having to worry about the internal physical structure of the chip. The structure of the packaging is linked inextricably to the socket or slot that the processor uses to interface to the motherboard.
Packaging has evolved over time from humble beginnings, responding to design needs as processors have grown larger and more complex. This section looks at the various packaging styles used in PC processors.
Dual Inline Package (DIP) The first Intel and compatible processors, used on the original PC, XT and clones, used standard dual inline or DIP packaging. "Dual inline" refers to two parallel sets of pins. DIP packaging is in fact the standard packaging used for most regular integrated circuits. The DRAM chips on your memory modules, and many of the support chips on your motherboard most likely use DIP packaging.
DIP packaging quickly became inadequate for use for processors when the number of signals going to and from them grew large. Modern processors have literally hundreds of signals that go to and from the motherboard, and since the DIP package only allows for two rows of pins this would have made for a really long package.
Single Edge Contact (SEC) The newest packaging style for desktop PCs, Single Edge Contact or SEC, is a move away from the single-chip- style packaging that Intel has used for all of its processors up to the Pentium Pro. The PPro had integrated secondary cache, inside the same chip package as the chip itself. With the creation of the Pentium II processor, Intel moved the secondary cache off-chip, but wanted to be able to maintain a special high-speed connection between it and the actual processor. To do this, they decided to not sell the Pentium II as a separate chip, but rather as an integrated package with the level 2 cache. SEC was the result. The SEC is actually a daughtercard, not a chip package at all. The processor itself is packaged using technology similar to regular PGA, but is mounted onto a small circuit board with a proprietary connector on its edge. The level 2 cache is also mounted onto this daughtercard, which goes into a special slot on the motherboard. This allows for a higher-speed interface to the secondary cache, since it is not on the motherboard as it is with the Pentium and Pentium with MMX motherboards. It also allows Intel to create a patented, proprietary motherboard interface for its new CPUs, which caused a fair bit of commotion at its introduction.
Pin Grid Array and Variations (PGA / SPGA / CPGA / PPGA) Pin Grid Array or PGA packaging is the standard used for most second through fifth generation processors, starting with the Intel 80286 over a decade ago. PGA packages are square or rectangular and have two or more rows of pins going around their perimeter. They are inserted into a special socket on the motherboard or daughtercard. PGA packaging was invented because newer processors with wider data and address buses required a large number of interface pins to the motherboard, and DIP packaging just was not up to the task. PGA comes in two different main material types. The standard PGA used on most processors until recently is made from a ceramic material, and is also called CPGA for that reason. Some newer processors use a plastic package, called PPGA. The plastic package is both less expensive and thermally superior to the CPGA. It has a raised metal square area on its surface for heat transfer to the heat sink that works better than the CPGA does.The Pentium Pro processor uses a special form of PGA called a "dual pattern PGA". This is of course because the Pentium Pro has a dual-chip package containing both the chip itself and its miniaturized, integrated secondary cache.
Land Grid Array The Land Grid array socket was built in response to the PGA. The LGA still contains pins — but the pins are already in the motherboard. The socket itself rests in the motherboard and has an enclosure at its top end, and the CPU is placed inside the enclosure and secured using a pressure lever. The CPU rests in the enclosure through a series of grooves, and communicates through electronic signals transmitted through transmission surfaces inside the socket.
Mobile Module (MMO) Notebook PCs have always represented the greatest design challenges for system makers due to their restrictions on size and weight, and the difficulty in cooling them. To combat this trend has been toward more and more miniaturization. Intel is continuing this trend by introducing mobile module packaging, which actually incorporates the processor, secondary cache, and chipset into a small module. One could argue that this is almost a motherboard in its own right; it isn't really, but it's pretty close.
PGA Versus LGA PGA sockets were originally used as the primary CPU controllers for Intel processors. However, PGA sockets have a notable weakness: the pins of the socket are easily damaged, rendering these and the CPU useless. Even building PGA sockets to ensure that zero actual pressure is required to insert the chip hasn't mitigated this problem. However, it's been argued that processors should not be changed or removed often, if at all, rendering this weakness something of a moot point. Both Intel and AMD use PGA and LGA sockets.
Processor Socket and Slot Types The purpose of the motherboard socket originally was just to provide a place to insert the processor into the motherboard. As such, it was no different than the sockets that were put on the board for most of the other PC components. However, over the last few years Intel, the primary maker of processors in the PC world, has defined several interface standards for PC motherboards. These are standardized socket and slot specifications to be used with various processors that are designed to use these standard sockets. What is significant about the creation of these standards is that Intel's two main competitors, AMD and Cyrix, have been able to use these standards as well in their quest for compatibility with Intel. While packages and sockets/slots do change over time, the presence of standards allows for better implementations by motherboard makers, who can make boards that hopefully support future processors more easily than if each board had to be tailored to a specific chip.
CPU Socket Specifications
Chip Class Socket Pins Layout Voltage
486 Socket 1 169 17x17 PGA 5V Socket 2 238 19x19 PGA 5V Socket 3 237 19x19 PGA 5V/3.3V Socket 61 235 19x19 PGA 3.3V
586 Socket 4 273 21x21 PGA 5V Socket 5 320 37x37 SPGA 3.3V/3.5V Socket 7 321 37x37 SPGA VRM
686 Socket 8 387 Dual-pattern SPGA Auto VRM Slot 1 (SC242) 242 Slot Auto VRM Socket 370 370 37x37 SPGA Auto VRM
Intel P4/Core Socket 423 423 39x39 SPGA Auto VRM Socket 478 478 26x26 mPGA Auto VRM Socket T (LGA775) 775 30x33 LGA Auto VRM LGA1156 (Socket H) 1156 40x40 LGA Auto VRM LGA1366 (Socket B) 1366 41x43 LGA Auto VRM LGA1155 (Socket H2) 1155 40x40 LGA Auto VRM
AMD K7 class Slot A 242 Slot Auto VRM Socket A (462) 462 37x37 SPGA Auto VRM
AMD K8 class Socket 754 754 29x29 mPGA Auto VRM Socket 939 939 31x31 mPGA Auto VRM Socket 940 940 31x31 mPGA Auto VRM Socket AM2 940 31x31 mPGA Auto VRM Socket AM2+ 940 31x31 mPGA Auto VRM Socket AM3 9412 31x31 mPGA Auto VRM Socket AM3+ 9412 31x31 mPGA Auto VRM Socket F (1207 FX) 1207 35x35 LGA Auto VRM
Server/Workstation Slot 2 (SC330) 330 Slot Auto VRM Socket 603 603 31x25 mPGA Auto VRM Socket 604 604 31x25 mPGA Auto VRM Socket PAC418 418 38x22 split SPGA Auto VRM Socket PAC611 611 25x28 mPGA Auto VRM LGA771 (Socket J) 771 30x33 LGA Auto VRM Socket M (PGA478MT) 478 26x26 PGA Auto VRM LGA1567 1567 38x43 LGA Auto VRM Socket 940 940 31x31 mPGA Auto VRM Socket F (1207 FX) 1207 35x35 LGA Auto VRM
Socket 6 was never actually implemented in systems. LGA = Land grid array FC-PGA2 = FC-PGA with an integrated heat spreader (IHS) Overdrive = Retail upgrade processors Socket has 941 pins, but CPUs for Socket AM3 have 938 pins. PGA = Pin grid array FC-PGA = Flip-chip pin grid array PAC = Pin array cartridge
VRM = Voltage regulator module with variable voltage output determined by module type or manual jumpers Auto VRM = Voltage regulator module with automatic voltage selection determined by processor voltage ID (VID)pins PPGA = Plastic pin grid array SECC = Single edge contact cartridge SEPP = Single edge processor package SPGA = Staggered pin grid array mPGA = Micro pin grid array
Supported Processors Introduced
486 SX/SX2, DX/DX2, DX4 OD Apr. 1989 486 SX/SX2, DX/DX2, DX4 OD, 486 Pentium OD Mar. 1992 486 SX/SX2, DX/DX2, DX4, 486 Pentium OD, AMD 5x86 Feb. 1994 486 DX4, 486 Pentium OD Feb. 1994
Pentium 60/66, OD Mar. 1993 Pentium 75-133, OD Mar. 1994 Intel Pentium 75-233+, MMX, OD, AMD K5/K6, Cyrix M1/II Jan. 1997
Intel Pentium Pro, OD Nov. 1995 Intel Pentium II/III SECC, Celeron SEPP May 1997 Intel Celeron/Pentium III PPGA/FC-PGA, VIA/Cyrix III/C3 Nov. 1998
Intel Pentium 4 FC-PGA Nov. 2000 Intel Pentium 4/Celeron FC-PGA2, Celeron D Oct. 2001 Intel Pentium 4/Extreme Edition, Pentium D, Celeron D, Pentium dual-core, Core2 June 2004 Intel Pentium, Core i3/i5/i7, Xeon Sept. 2009 Intel Core i7, Xeon Nov. 2008 Intel Core i7, i5, i3 Jan. 2011
AMD Athlon SECC June 1999 AMD Athlon/Athlon XP/Duron PGA/FC-PGA June 2000
AMD Athlon 64 Sep. 2003 AMD Athlon 64 v.2 June 2004 AMD Athlon 64 FX, Opteron Apr.2003 AMD Athlon 64/64FX/64 X2, Sempron, Opteron, PhenomMay 2006 AMD Athlon 64/64 X2, Opteron, Phenom X2/X3/X4. II X4 Nov. 2007 AMD Athlon II, Phenom II, Sempron Feb. 2009 AMD ―Bulldozer‖ processors Mid-2011 (expected) AMD Athlon 64 FX, Opteron Aug. 2006 Intel Pentium II/III Xeon Apr. 1998 Intel Xeon (P4) May 2001 Intel Xeon (P4) Oct. 2003 Intel Itanium May 2001 Itanium 2 July 2002 Intel Xeon Jun. 2006 Intel Xeon Jan. 2006 Intel Xeon April 2011 AMD Athlon 64 FX, Opteron Apr. 2003 AMD Athlon 64 FX, Opteron Aug. 2006
Socket 775 with Processor
PGA 775 Socket LGA 775 Processor
Socket 1155 With Porcessor
PGA1155 Socket LGA 1155 Processor
Microprocessor Manufacturing Technology Semiconductors are fabricated on wafers. Each wafer can contain dozens of individual dies (the actual semiconductor device that goes into a chip). The smaller each die is, the more dies you can fit on each wafer. Smaller process sizes demand an investment in more expensive equipment; but after that initial cost, the per-wafer cost difference is not huge. So by cramming more dies on each wafer, you can significantly decrease the cost to manufacture your product. This is where Moore's law comes from. Moore's law states that roughly every two years, you can pack twice as many transistors into a chip at about the same cost. Historically, the industry has managed a transition to a smaller process node (such as the transitions from 130 nm to 90 nm to 65 nm) about once every two years. And each time, you can fit about twice as many transistors into the same physical area.
Details of all Semiconductor manufacturing processes are as follow: - 10 µm — 1971 Semiconductor companies Intel. Products Intel 4004CPU launched in 1971 and Intel 8008CPU launched in 1972 were manufactured using this process.
3 µm — 1975 Semiconductor companiesIntel. Products Intel 8085CPU launched in 1975 and Intel 8088CPU launched in 1979 were manufactured using this process.
1.5 µm — 1982 Semiconductor companies Intel and IBM. Products Intel 80286CPU launched in 1982 was manufactured using this process.
1 µm — 1985 Semiconductor companies Intel and IBM. ProductsIntel 80386CPU launched in 1985 was manufactured using this process.
800 nm — 1989 Semiconductor companies Intel and IBM. Products Intel 486CPU launched in 1989, microSPARC I launched in 1992 and First Intel P5Pentium CPUs at 60 MHz and 66 MHz launched in 1993 were manufactured using this process.
600 nm — 1994 Semiconductor companies Intel and IBM. Products Intel 80486DX4CPU launched in 1994 and Intel Pentium CPUs at 75 MHz, 90 MHz and 100 MHz were manufactured using this process.IBM/MotorolaPowerPC 601, the first PowerPC chip, was produced in 0.6 µm.
350 nm — 1995 Semiconductor companies Intel and IBM. IntelPentium Pro (1995), Pentium (P54CS, 1995), and initial Pentium IICPUs (Klamath, 1997). AMDK5 (1996) and original AMD K6 (Model 6, 1997) CPUs.NEC VR4300, used in the Nintendo 64 game console.Parallax Propeller, 8 core microcontroller.
250nm — 1997 The 250 nanometer (250 nm) process refers to a level of semiconductor process technology that was reached by most manufacturers in the 1997-1998 timeframe.Products are The DEC Alpha 21264A, in 1999. The AMD K6- 2Chomper and Chomper Extendedon May 28, 1998. The mobile Pentium MMXTillamook, in August 1997. The Pentium IIDeschutes, Pentium IIIKatmai, Dreamcast CPU and GPU. The initial PlayStation 2's Emotion Engine CPU.
180 nm — 1999 The 180 nanometer (180 nm) process refers to the level of semiconductor process technology that was reached in the 1999-2000 timeframe by most leading semiconductor companies, like Intel, Texas Instruments, IBM, and TSMC.Products are Intel Coppermine E- October, 1999. Intel Celeron (Willamette) - May, 2002. Motorola PowerPC 7445 and 7455 (Apollo 6) - January, 2002
130 nm — 2002 The 130 nanometer (130 nm) process refers to the level of semiconductor process technology that was reached in the 2000–2001 timeframe, by most leading semiconductor companies, like Intel, Texas Instruments, IBM, and TSMC. Products are Motorola PowerPC 7447 and 7457 2002, IBM Gekko (Nintendo GameCube), IBM PowerPC G5 970 - October 2002 - June 2003, Intel Pentium IIITualatin and Coppermine - 2001-04, Intel CeleronTualatin-256 - 2001- 10-02, Intel Pentium MBanias - 2003-03-12, Intel Pentium 4 Northwood- 2002-01-07, Intel Celeron Northwood- 128 - 2002-09-18, Intel XeonPrestonia and Gallatin - 2002-02-25, VIA C3 – 2001, AMD Athlon XP Thoroughbred, Thorton, and Barton, AMD Athlon MP Thoroughbred - 2002-08-27, AMD Athlon XP-M Thoroughbred, Barton, and Dublin, AMD DuronApplebred - 2003-08-21, AMD K7 Sempron Thoroughbred-B, Thorton, and Barton - 2004-07-28, AMD K8 Sempron Paris - 2004-07-28, AMD Athlon 64Clawhammer and Newcastle - 2003-09-23, AMD Opteron Sledgehammer - 2003-06-30, Elbrus 2000 1891ВМ4Я (1891VM4YA) - 2008-04-27, MCST-R500S 1891BM3 - 2008-07-27 and Vortex 86SX.
90 nm — 2004 The 90 nanometer (90 nm) process refers to the level of CMOS process technology that was reached in the 2004– 2005 timeframe, by most leading semiconductor companies, like Intel, AMD, Infineon, Texas Instruments, IBM, and TSMC. Products are IBM PowerPC G5 970FX– 2004, IBM PowerPC G5 970MP– 2005, IBM PowerPC G5 970GX– 2005, IBM "Waternoose" Xbox 360 Processor – 2005, IBM/Sony/ Toshiba Cell Processor– 2005, Intel Pentium 4 Prescott - 2004-02, Intel Celeron D Prescott-256 - 2004-05, Intel Pentium MDothan - 2004-05, Intel Celeron M Dothan-1024 - 2004-08, Intel Xeon Nocona, Irwindale, Cranford, Potomac, Paxville - 2004-06, Intel Pentium D Smithfield - 2005-05, AMD Athlon 64 Winchester, Venice, San Diego, Orleans - 2004-10, AMD Athlon 64 X2 Manchester, Toledo, Windsor - 2005-05, AMD Sempron Palermo and Manila - 2004-08, AMD Turion 64 Lancaster and Richmond - 2005-03, AMD Turion 64 X2 Taylor and Trinidad - 2006-05, AMD Opteron Venus, Troy, and Athens - 2005-08, AMD Dual-core Opteron Denmark, Italy, Egypt, Santa Ana, and Santa Rosa, VIA C7 - 2005-05, Loongson (Godson) 2Е STLS2E02 - 2007-04, Loongson (Godson) 2F STLS2F02 - 2008-07, MCST-4R - 2010-12 and Elbrus-2C+ - 2011-11.
65 nm — 2006
The 65 nanometer (65 nm) process is an advanced lithographicnode used in volume CMOSsemiconductor fabrication. Printed linewidths (i.e., transistor gate lengths) can reach as low as 25 nm on a nominally 65 nm process, while the pitch between two lines may be greater than 130 nm. For comparison, cellular ribosomes are about 20 nm end-to-end. A crystal of bulk silicon has a lattice constant of 0.543 nm, so such transistors are on the order of 100 atoms across. By September 2007, Intel, AMD, IBM, UMC, Chartered and TSMC were producing 65 nm chips.
Products are Intel Pentium 4 (Cedar Mill) – 2006-01-16, Intel Pentium D 900-series – 2006-01-16, Intel Celeron D (Cedar Mill cores) – 2006-05-28, Intel Core – 2006-01-05, Intel Core 2 – 2006-07-27, Intel Xeon (Sossaman) – 2006-03-14, AMD Athlon 64 series (starting from Lima) – 2007-02-20, AMD Turion 64 X2 series (starting from Tyler)- 2007-05-07, AMD Phenom series, IBM's Cell Processor – PlayStation 3 – 2007-11-17, IBM's z10, Microsoft Xbox 360 "Falcon" CPU – 2007–09, Microsoft Xbox 360 "Opus" CPU – 2008, Microsoft Xbox 360 "Jasper" CPU – 2008–10, Microsoft Xbox 360 "Jasper" GPU – 2008–10, Sun UltraSPARC T2 – 2007–10, AMD Turion Ultra – 2008-06, TI OMAP 3 Family – 2008-02, VIA Nano – 2008-05, Loongson – 2009, NVIDIA GeForce 8800GT GPU – 2007 and Nikon Expeed 2 – 2010. 45 nm — 2008 The 45 nanometer (45 nm) technology node should refer to the average half-pitch of a memory cell manufactured at around the 2007–2008 time frame. Matsushita and Intel started mass producing 45 nm chips in late 2007, and AMD started production of 45 nm chips in late 2008, while IBM, Infineon, Samsung, and Chartered Semiconductor have already completed a common 45 nm process platform. At the end of 2008, SMIC was the first China-based semiconductor company to move to 45 nm, having licensed the bulk 45 nm process from IBM. Products are Matsushita’s 45 nm Uniphier and Wolfdale, Yorkfield, Yorkfield XE and Penryn are current Intel cores sold under the Core 2 brand. Intel Core i7 series processors, i5 750 (Lynnfield and Clarksfield).Pentium Dual- CoreWolfdale-3Mare current Intel mainstream dual core sold under the Pentium brand. Diamondville, Pineview are current Intel cores with Hyper-Threading sold under the Intel Atom brand. AMDDeneb (Phenom II) and Shanghai (Opteron) Quad-Core Processors, Regor (Athlon II) dual core processors Caspian (Turion II) mobile dual core processors.AMD (Phenom II) "Thuban" Six-Core Processor (1055T).Xenon on Xbox 360 S model.Cell Broadband Engine in PlayStation 3 Slim model – September 2009.Samsung S5PC110, as known as Hummingbird. Texas InstrumentsOMAP 3 and 4 series.IBMPOWER7 and z196.FujitsuSPARC64 VIIIfx series. The Wii U "Espresso" IBM CPU.
32 nm — 2010 The 32 nanometer (32 nm) node is the step following the 45 nanometer process in CMOSsemiconductor device fabrication. "32 nanometer" refers to the average half-pitch (i.e., half the distance between identical features) of a memory cell at this technology level. Intel and AMD both produced commercial microchips using the 32 nanometer process in the early 2010s. Intel's Core i3 and i5 processors, released in January 2010, were among the first mass-produced processors to use 32 nm technologies. Intel's second-generation Core processors, codenamed Sandy Bridge, also used the 32 nm manufacturing process. Intel's 6-core processor, codenamed Gulftown and built on the Westmere architecture, was released on 16 March 2010 as the Core i7 980x Extreme Edition,AMD also released 32 nm SOI processors in the early 2010s. AMD's FX Series processors, codenamed Zambezi and based on AMD's Bulldozer architecture, were released in October 2011. The technology utilised a 32 nm SOI process, two CPU cores per module, and up to four modules.
22 nm — 2012 The 22 nanometer (22 nm) is the CMOS process step following the 32 nm process in CMOSsemiconductor device fabrication. Ivy Bridge is a codename line of Intel processors based on the 22 nm manufacturing process.The typical half-pitch (i.e., half the distance between identical features in an array) for a memory cell using the process is around 22 nm. It was first introduced by semiconductor companies in 2008 for use in memory products, while first consumer-level CPU deliveries started in April 2012.Intel Core i7 and Intel Core i5 processors based on Intel's Ivy Bridge 22 nm technologies for series 7 chip-sets.
14 nm — est. 2014 The 14 nanometer (14 nm) node is the technology node following the 22 nm/(20 nm) node. The exact naming of this technology nodes as "16 nm" originally came from the International Technology Roadmap for Semiconductors (ITRS). By current estimates the 14 nm technology is projected to be reached by semiconductor companies in the 2014 timeframe.[1] It has been claimed that transistors cannot be scaled below the size achievable at 16 nm due to quantum tunnelling, regardless of the materials used.
Processor Troubleshooting Techniques Problem Identification Possible Cause Resolution
System beeps on startup, fan Improperly seated or failing Reseat or replace graphics adapter. is running, no cursor onscreen. graphics adapter. Use known-good spare for testing.
System powers up, fan is Processor not properly Reseat or remove /reinstall processor and running, no beep or cursor. installed. heatsink.
Locks up during or shortly Poor heat dissipation. Check CPU heatsink fan; replace if necessary after POST. with one of higher capacity.
Improper voltage settings. Set motherboard for proper core processor voltage.
Improper CPU identification Old BIOS. Update BIOS from manufacturer. during POST. Board not configured properly. Check manual and set board accordingly to proper bus and multiplier settings.
System won‘t start after Processor not properly installed. Reseat or remove/reinstall processor and new processor is installed. heatsink.
Motherboard can‘t use Verify motherboard support. new processor.
Unlocked processor Reset motherboard to use only working cores. Core failed.
OS will not boot. Poor heat dissipation. Check CPU fan (replace if necessary); it might need a higher-capacity heatsink or heatsink/fan on the North Bridge chip. Applications will not Improper drivers or incompatible hardware; install or run. update drivers and check for compatibility issues. System appears to work, Monitor turned off or failed. Check monitor and power to monitor. but no video is displayed. Replace with known-good spare for testing.
Things to Know when Upgrading or Buying a Processor for Your Computer
Socket Type This is very important. If you purchase the wrong CPU for your socket, it will not fit. Be sure to check a list similar to the one found here that the CPU you are considering is compatible with your PC. If you don't know what socket type you have, check what processor you have, refer to the table and locate your socket type.
Processor Manufacturer/Brand The two most popular are Intel, and AMD, both of which you most likely have heard of if you are considering purchasing a new processor. When choosing which brand to buy, consider what socket type first of all, then consider price and what the computer will be used for. Generally, AMD processors are associated with high-end gaming computers, but that is not always the case as Intel processors can operate under gaming conditions just as effectively.
Clock Speed
Clock speed, typically measured and displayed as gigahertz (GHz) is how fast the processor is operating under factory conditions. It is possible to modify this manually via overclocking, however be warned that it does shorten the life of your processor and you may need extra cooling to do so. If you are looking at a dual, quad, or octa+ processor, keep in mind that the clock speed is the speed for each individual core, treating it as a separate processor.
Power Consumption
This is usually not an issue, but if you have an older power supply unit, it can become one. Just be sure that your power supply has enough wattage to support the requirements of the new processor.
Computer Memory
Memory is the workspace for the processor. It is a temporary storage area where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only as long as the computer has electrical power or is not reset. Before the computer is shut down or reset, any data that has been changed in memory should be saved to a more permanent storage device (usually a hard disk) so it can be reloaded into memory in the future.
Memory often is called RAM, for random access memory. Main memory is called RAM because you can randomly (as opposed to sequentially) access any location. This designation is somewhat misleading and often misinterpreted. Read-only memory (ROM), for example, is also randomly accessible, yet it is usually differentiated from the system RAM because it maintains data without power and can‘t normally be written to. Although a hard disk can be used as virtual random access memory, we don‘t consider that RAM either.
Over the years, the definition of RAM has changed from a simple acronym to become something that means the primary memory workspace the processor uses to run programs, which usually is constructed out of a type of chip called dynamic RAM (DRAM).
Physically, the main memory in a system is a collection of chips or modules containing chips that are usually plugged into the motherboard. These chips or modules vary in their electrical and physical designs and must be compatible with the system into which they are being installed to function properly. This chapter discusses the various types of chips and modules that can be installed in different systems.
To better understand physical memory in a system, you should understand what types of memory are found in a typical PC and what the role of each type is. Three main types of physical memory are used in modern PCs. (Remember, I‘m talking about the type of memory chip, not the type of module that memory is stored on.)
ROM—Read-only memory DRAM—Dynamic random access memory SRAM—Static RAM
The only type of memory you normally need to purchase and install in a system is DRAM. The other types are built in to the motherboard (ROM), processor (SRAM), and other components such as the video card, hard drives, and so on.
ROM Read-only memory, or ROM, is a type of memory that can permanently or semi permanently store data. It is called read-only because it is either impossible or difficult to write to. ROM also is often referred to as nonvolatile memory because any data stored in ROM remains there, even if the power is turned off. As such, ROM is an ideal place to put the PC‘s startup instructions—that is, the software that boots the system.
Note that ROM and RAM are not opposites, as some people seem to believe. Both are simply types of memory. In fact, ROM technically could be classified as a subset of the system‘s RAM. In other words, a portion of the system‘s random access memory address space is mapped into one or more ROM chips. This is necessary to contain the software that enables the PC to boot; otherwise, the processor would have no program in memory to execute when it was powered on. The main ROM BIOS is contained in a ROM chip on the motherboard, but there are also adapter cards with ROMs on them. ROMs on adapter cards contain auxiliary BIOS routines and drivers needed by the particular card, especially for those cards that must be active early in the boot process, such asvideo cards. Cards that don‘t need drivers active at boot time typically don‘t have a ROM because those drivers can be loaded from the hard disk later in the boot process. Most systems today use a type of ROM called electrically erasable programmable ROM (EEPROM), which is a form of flash memory. Flash is a truly nonvolatile memory that is rewritable, enabling users to easily update the ROM or firmware in their motherboards or any other components (video cards, SCSI cards, peripherals, and so on).
DRAM Dynamic RAM (DRAM) is the type of memory chip used for most of the main memory in a modern PC. The main advantages of DRAM are that it is very dense, meaning you can pack a lot of bits into a small chip, and it is inexpensive, which makes purchasing large amounts of memory affordable.
The memory cells in a DRAM chip are tiny capacitors that retain a charge to indicate a bit. The problem with DRAM is that it is dynamic—that is, its contents can be changed. With every keystroke or every mouse swipe, the contents of RAM change. And the entire contents of RAM can be wiped outby a system crash. Also, because of the design, it must be constantly refreshed; otherwise, the electrical charges in the individual memory capacitors drain and the data is lost. Refresh occurs when the system memory controller takes a tiny break and accesses all the rows of data in the memory chips. The standard refresh time is 15ms (milliseconds), which means that every 15ms, all the rows in the memory are automatically read to refresh the data. Unfortunately, refreshing the memory takes processor time away from other tasks because each refresh cycle takes several CPU cycles to complete. In older systems, the refresh cycling could take up to 10% or more of the total CPU time, but with modern systems running in the multigigahertz range, refresh overhead is now on the order of a fraction of a percent or less of the total CPU time. Some systems allow you to alter the refresh timing parameters via the CMOS Setup. The time between refresh cycles is known as tREF and is expressed not in milliseconds, but in clock cycles.
Cache Memory: SRAM Another distinctly different type of memory exists that is significantly faster than most types of DRAM. SRAM stands for static RAM, which is so named because it does not need the periodic refresh rates like DRAM. Because of the way SRAMs are designed, not only are refresh rates unnecessary, but SRAM is much faster than DRAM and much more capable of keeping pace with modern processors. SRAM memory is available in access times of 0.45ns or less, so it can keep pace with processors running 2.2GHz or faster. This is because of the SRAM design, which calls for a cluster of six transistors for each bit of storage. The use of transistors but no capacitors means that refresh rates are not necessary because there are no capacitors to lose their charges over time. As long as there is power, SRAM remembers what is stored. With these attributes, why don‘t we use SRAM for all system memory? The answers are simple.Compared to DRAM, SRAM is much faster but also much lower in density and much more expensive. The lower density means that SRAM chips are physically larger and store fewer bits overall. The high number of transistors and the clustered design mean that SRAM chips are both physically larger and much more expensive to produce than DRAM chips. For example, a high-density DRAM chip might store up to 4Gb (512MB) of RAM, whereas similar-sized SRAM chips can only store up to 72Mb (9MB). The high cost and physical constraints have prevented SRAM from being used as the main memory for PC systems.
Comparing DRAM and SRAM
Type Speed Density Cost
DRAM Slow High Low
SRAM Fast Low High
Even though SRAM is impractical for PC use as main memory, PC designers have found a way to use SRAM to dramatically improve PC performance. Rather than spend the money for all RAM to be SRAM memory, they design in a small amount of high-speed SRAM memory, used as cache memory, which is much more cost effective. The SRAM cache runs at speeds close to or even equal to theprocessor and is the memory from which the processor usually directly reads from and writes to.
During read operations, the data in the high-speed cache memory is resupplied from the lower-speed main memory or DRAM in advance. To convert access time in nanoseconds to MHz, use the following formula:
1 / nanoseconds × 1000 = MHz
Likewise, to convert from MHz to nanoseconds, use the following inverse formula:
1 / MHz × 1000 = nanoseconds
Today we have memory that runs faster than 1GHz (1 nanosecond), but up until the late 1990s, DRAM was limited to about 60ns (16MHz) in speed. Up until processors were running at speeds of 16MHz, the available DRAM could fully keep pace with the processor and motherboard, meaning that there was no need for cache. However, as soon as processors crossed the 16MHz barrier, the available DRAM could no longer keep pace, and SRAM cache began to enter PC system designs. This occurred way back in 1986 and 1987 with the debut of systems with the 386 processor running at speeds of 16MHz to 20MHz or faster. These were among the first PC systems to employ what‘s called cache memory, a high-speed buffer made up of SRAM that directly feeds the processor. Because the cache can run at the speed of the processor, it acts as a buffer between the processor and the slower DRAM in the system. The cache controller anticipates the processor‘s memory needs and preloads the high-speed cache memory with data. Then, as the processor calls for a memory address, the data can be retrieved from the high-speed cache rather than the much lower-speed main memory. JEDEC is the semiconductor engineering standardization body of the Electronic Industries Alliance (EIA), a trade association that represents all areas of the electronics industry. JEDEC, which was created in 1960, governs the standardization of all types of semiconductor devices, integrated circuits, and modules. JEDEC has about 300 member companies, including memory, chipset, and processor manufacturers and practically any company involved in manufacturing computer equipment using industry-standard components.
Speed and Performance The speed and performance issues with memory are confusing to some people because of all the different ways to express the speeds of memory and processors. Memory speed was originally expressed in nanoseconds (ns), whereas the speeds of newer forms of memory are usually expressed in megahertz (MHz) and megabytes per second (MBps) instead. Processor speed was originally expressed in megahertz (MHz), whereas most current processor speeds are expressed in gigahertz (GHz). Although all these different speed units might seem confusing, it is relatively simple to translate from one to the other. Memory speeds have often been expressed in terms of their cycle times (or how long it takes for one cycle), whereas processor speeds have almost always been expressed in terms of their cycle speeds (number of cycles per second). Cycle time and cycle speed are actually just different ways of saying the same thing; that is, you can quote chip speeds in cycles per second, or seconds per cycle, and mean the same thing.
Over the evolutionary life of the PC, main memory (what we call RAM) has had a difficult time keeping up with the processor, requiring several levels of high-speed cache memory to intercept processor requests for the slower main memory. More recently, however, systems using DDR, DDR2, and DDR3 SDRAM have memory bus transfer rates (bandwidth) capable of equaling that of the external processor bus. When the speed of the memory bus equals the speed of the processor bus (or some even multiple thereof), main memory performance is closest to optimum for that system.
MHz = Million cycles per second MTps= Million transfers per second MBps = Million bytes per second DIMM = Dual inline memory module SODIMM = Small outline DIMM SIMM = Single inline memory module RIMM = Rambus inline memory module
PC Memory Types and Performance Levels
Desktop Laptop Max Memory Years Module Module Clock Type Popular Type Type Voltage Speed
Fast Page Mode 1987–1995 30/72-pin 72/144-pin
(FPM) DRAM SIMM SODIMM 5V 22MHz Extended Data 1995–1998 72-pin 72/144-pin 5V 33MHz Out (EDO) DRAM SIMM SODIMM
Single Data Rate 1998–2002 168-pin 144-pin 3.3V 133MHz (SDR) SDRAM DIMM SODIMM
Double Data Rate 2002–2005 184-pin 200-pin 2.5V 400MTps (DDR) SDRAM DIMM SODIMM
DDR2 SDRAM 2005–2008 240-pin 200-pin 1.8V 1,066MTps
DDR2 DIMM SODIMM
DDR3 SDRAM 2008+ 240-pin 204-pin 1.5V 2,133MTps DDR3 DIMM SODIMM
Fast Page Mode DRAM Standard DRAM is accessed through a technique called paging. Normal memory access requires that a row and column address be selected, which takes time. Paging enables faster access to all the data within a given row of memory by keeping the row address the same and changing only the column.Memory that uses this technique is called Page Mode or Fast Page Mode memory. Other variations on Page Mode were called Static Column or Nibble Mode memory.Paged memory is a simple scheme for improving memory performance that divides memory into pages ranging from 512 bytes to a few kilobytes long. The paging circuitry then enables memory locations in a page to be accessed with fewer wait states. If the desired memory location is outside the current page, one or more wait states are added while the system selects the new page.
Extended Data Out RAM In 1995, a newer type of DRAM called extended data out (EDO) RAM became available for Pentium systems. EDO, a modified form of FPM memory, is sometimes referred to as Hyper Page mode. EDO was invented and patented by Micron Technology, although Micron licensed production to many other memory manufacturers. EDO memory consists of specially manufactured chips that allow a timing overlap between successive accesses. The name extended data out refers specifically to the fact that, unlike FPM, the data output drivers on the chip are not turned off when the memory controller removes the column address to begin the next cycle. This enables the next cycle to overlap the previous one, saving approximately 10ns per cycle.EDO RAM generally came in 72-pin SIMM form.
SDRAM SDRAM is short for synchronous DRAM, a JEDEC standard for a type of DRAM that runs in synchronization with the memory bus. SDRAM delivers information in very high-speed bursts using a high-speed clocked interface. SDRAM removes most of the latency involved in asynchronous DRAM because the signals are already in synchronization with the motherboard clock.
Starting in 1996 with the 430VX and 430TX, most of Intel‘s chipsets began to support industry-standard SDRAM, and in 1998 the introduction of the 440BX chipset caused SDRAM to eclipse EDO as the most popular type on the market. SDRAM performance is dramatically improved over that of FPM or EDO RAM. However, because SDRAM is still a type of DRAM, the initial latency is the same, but burst mode cycle times are muchfaster than with FPM or EDO. Besides being capable of working in fewer cycles, SDRAM is capable of supporting up to 133MHz (7.5ns) system bus cycling. Most PC systems sold from 1998 through 2002 included SDRAM memory.SDRAM normally came in 168-pin DIMMs, running at several speeds.
DDR SDRAM DDR SDRAM memory is a JEDEC standard that is an evolutionary upgrade in which data transfers twice as quickly as standard SDRAM. Instead of doubling the actual clock rate, DDR memory achieves the doubling in performance by transferring twice per transfer cycle: once at the leading (falling) edge and once at the trailing (rising) edge of the cycle. This effectively doubles the transfer rate, even though the same overall clock and timing signals are used. To eliminate confusion with DDR, regular SDRAM is often called single data rate (SDR). DDR SDRAM first came to market in the year 2000 and was initially used on high-end graphics cards because there were no motherboard chipsets to support it at the time. DDR finally became popular in 2002 with the advent of mainstream supporting motherboards and chipsets. From 2002 through 2005, DDR was the most popular type of memory in mainstream PCs. DDR SDRAM uses a DIMM module design with 184 pins.
DDR2 SDRAM DDR2 is a faster version of DDR memory. It achieves higher throughput by using differential pairs of signal wires to allow faster signaling without noise and interference problems. DDR2 is still double data rate just as with DDR, but the modified signaling method enables you to achieve higher clock speeds with more immunity to noise and crosstalk between the signals. The additional signals required for differential pairs add to the pin count—DDR2 DIMMs have 240 pins, which is more than the 184 pins of DDR. The original DDR specification officially topped out at 400MHz (although faster unofficial overclocked modules were produced), Whereas DDR2 starts at 400MHz and goes up to an official maximum of 1,066MHz. In addition to providing greater speeds and bandwidth, DDR2 has other advantages. It uses lower voltage than conventional DDR (1.8V versus 2.5V), so power consumption and heat generation are reduced.
DDR3 SDRAM DDR3 is the latest JEDEC memory standard. It enables higher levels of performance along with lower power consumption and higher reliability than DDR2. JEDEC began working on the DDR3 specification in June 2002, and the first DDR3 memory modules and supporting chipsets (versions of the Intel3x series) were released for Intel-based systems in mid-2007. Due to initial high cost and limited support, DDR3 didn‘t start to become popular until late 2008 when Intel released the Core i7 processor, which included an integrated tri-channel DDR3 memory controller. DDR3 modules use advanced signaling techniques, including self-driver calibration and data synchronization, along with an optional onboard thermal sensor. DDR3 memory runs on only 1.5V, which is nearly 20% less than the 1.8V that DDR2 memory uses. The lower voltage combined with higher efficiency reduces overall power consumption by up to 30% compared to DDR2. The 240-pin DDR3 modules are similar in pin count, size, and shape to the DDR2 modules; however, the DDR3 modules are incompatible with the DDR2 circuits and are designed with different keying to make them physically noninterchangeable.
RDRAM Rambus DRAM (RDRAM) was a proprietary (non-JEDEC) memory technology found mainly in certain Intel- based Pentium III and 4 systems from 2000 through 2002. Very few of these systems are still in use today. For more information about RDRAM and RIMM modules, see Chapter 6, ―Memory,‖ in Upgrading and Repairing PCs, 19th edition.Not an acronym, RIMM is a trademark of Rambus Inc., perhaps a clever play on the acronym DIMM, a competing form factor. A RIMM is a custom memory module that varies in physical specification based on whether it is a 16-bit or 32-bit module. The 16-bit modules have 84 pins and two keying notches, while 32-bit modules have 232 pins and only one keying notch, reminiscent of the trend in SDRAM-to-DDR evolution.
Memory Modules A chip was needed that was both soldered and removable, which was made possible by using memory modules instead of individual chips. Early modules had one row of electrical contacts and were called SIMMs (single inline memory modules), whereas later modules had two rows and were called DIMMs (dual inline memory modules) or RIMMs (Rambus inline memory modules). These small boards plug into special connectors on a motherboard or memory card. The individual memory chips are soldered to the module, so removing and replacing them is impossible. Instead, you must replace the entire module if any part of it fails. The module is treated as though it were one large memory chip. Several types of SIMMs, DIMMs, and RIMMs have been commonly used in desktop systems. The various types are often described by their pin count, memory row width, or memory type. SIMMs, for example, are available in two main physical types—30-pin (8 bits plus an option for 1 additional parity bit) and 72-pin (32 bits plus an option for 4 additional parity bits)—with various capacities and other specifications. The 30-pin SIMMs are physically smaller than the 72-pin versions, and either version can have chips on one or both sides. SIMMs were widely used from the late 1980s to the late 1990s but have become obsolete. DIMMs are available in four main types. SDR (single data rate) DIMMs have 168 pins, one notch on either side, and two notches along the contact area. DDR DIMMs, on the other hand, have 184 pins, two notches on each side, and only one offset notch along the contact area. DDR2 and DDR3 DIMMs have 240 pins, two notches on each side, and one near the center of the contact area. All DIMMs are either 64 bits (non-ECC/parity) or 72 bits (data plus parity or error-correcting code [ECC]) wide. The main physical difference between SIMMs and DIMMs is that DIMMs have different signal pins on each side of the module, resulting in two rows of electrical contacts. That is why they are called dual inline memory modules, and why with only 1 inch of additional length, they have many more pins than a SIMM.
SIMM, DIMM, and RIMM Capacities
Capacity Standard Depth×Width Parity/ECC Depth×Width
30-Pin SIMM
256KB 256K×8 256K×9
1MB 1M×8 1M×9
4MB 4M×8 4M×9
16MB 16M×8 16M×9
72-Pin SIMM
1MB 256K×32 256K×36
2MB 512K×32 512K×36
4MB 1M×32 1M×36
8MB 2M×32 2M×36
16MB 4M×32 4M×36
32MB 8M×32 8M×36
64MB 16M×32 16M×36
128MB 32M×32 32M×36
168/184-Pin DIMM/DDR DIMM
8MB 1M×64 1M×72
16MB 2M×64 2M×72
32MB 4M×64 4M×72
64MB 8M×64 8M×72
128MB 16M×64 16M×72
256MB 32M×64 32M×72
512MB 64M×64 64M×72
1,024MB 128M×64 128M×72
2,048MB 256M×64 256M×72
240-Pin DDR2/DDR3 DIMM
256MB 32M×64 32M×72
512MB 64M×64 64M×72
1,024MB 128M×64 128M×72
2,048MB 256M×64 256M×72
4,096MB 512M×64 512M×72
184-Pin RIMM
64MB 32M× 16 32M× 18
128MB 64M× 16 64M× 18
256MB 128M× 16 128M× 18
512MB 256M× 16 256M× 18
1,024MB 512M× 16 512M× 18
Installing RAM in slot
Troubleshooting RAM 1. Have you added or replaced RAM? Is it installed properly? 2. Have you moved the computer? RAM modules can come loose. 3. Is it a new computer? RAM modules might not have been inserted properly. 4. Have you installed any new hardware upgrades? 5. Have you installed new software or might there be a virus problem? 6. Have you changed or installed patches for your operating system? 7. Do you have the correct RAM type? 8. Is the RAM module connectors tin or gold? 9. When your computer starts (boots) does it report the correct amount of RAM? 10. Do your system properties report the correct amount of RAM? 11. Are there any POST messages that indicate RAM problems? 12. Does the system report Parity errors or address failures whilst the system is running?
Any one of these can indicate a problem with the RAM module or something connected with it.
WARNING: Before you start troubleshooting remember that you are dealing with electricity that can KILL. Only work inside the computer case when the power has been switched off and disconnected. Never open the power source.
Step 3: Start by reading through this article to establish some ideas about what the problem might be and how to resolve it. There is no absolute order for diagnosing problems it's equal parts science and magic.
Step 4: Gather all the documentation that came with your computer, memory modules or MOBO (motherboard). You need information on make and model numbers, together with installation guides. If you are missing anything visit the PC or MOBO manufacturer’s web site. Most have excellent online documentation.
Step 5: Do you have the correct RAM? Check the MOBO or computer documentation for the type of memory module you should be using. Compare this with the memory module you have purchased. Look at the memory module; does the information on the module match with the sales invoice (have they sent you the correct product)? If you bought a name brand computer has the RAM purchased been tested on that particular computer? This can be an issue with Dell and other computers. You can check compatibility issues online through useful tools on www.kingston.com, www.crucial.com or the MOBO manufacturers own web site.
NOTE: Before the computer case is opened make sure that power is switched off and disconnected, press and hold the power button for 30 seconds to ensure residual power is lost and make sure that you are grounded to avoid damage due to static electricity. Use a grounding wrist strap or touch the metal case to discharge static electricity.
Now open the computer case to check the following.
Step 6: Is the RAM installed correctly? Some MOBOs must have their slots filled in a special sequence. Sometimes DIMMs must be in a specific sequence.
Step 7: Remove the memory modules from their slots. Take the opportunity to clean the slots on the motherboards and the memory module connectors. Use compressed air to blow dust away and clean contacts with a soft cloth. Don't use a vacuum cleaner if it touches any component it may create a short and cause damage to the motherboard or other components. Don't use solvent that may attract dust and never poke things like cotton buds in to slots. Check the memory module and memory slot contacts. They are either tin or gold. The color will tell you which they are. Mixing tin and gold can result in corrosion that prevents proper contact. Look for any sign of physical damage to the memory module, memory slots or the motherboard. With the last two you are looking at replacing the motherboard.
Step 8: Reseat the memory modules. You should hear an audible click when they are in place. Do not use too much force to reseat the memory module in to the slot this can cause damage to the module, slot or motherboard.
If you are still experiencing trouble try the following.
Step 9: Swap modules in to different slots. If you have more than one memory module try different combinations or one at a time. This might identify a faulty component.
Step 10: If you have changed or upgraded the memory modules try taking your system back to its original configuration. Does it still work? If yes then suspect a fault or compatibility problem. If no!! Sorry but you may have damaged the motherboard.
Step 11: If your compute isn't recognizing your entire RAM it might be a problem with the BIOS. Check with the motherboard or PC manufacturer’s web site for possible BIOS upgrades. Word of WARNING - BIOS upgrades can seriously damage your wealth. Make double sure that you have the correct BIOS update for your motherboard. Flash the wrong upgrade can result in needing a new motherboard.
Step 12: Check for viruses with an up to date virus checker. Some viruses cause problems that look like memory errors.
Step 13: Try removing recently installed hardware or software. Sometimes operating systems misinterpret problems as memory related.
Things to consider before upgrading RAM
1. QVL – Qualified Vendors List: In short, this is a list offered on the manufacturer motherboard page which states which RAM was tested and is guaranteed to be compatible with said motherboard. Make sure to buy RAM that is on your motherboard‘s QVL to ensure maximum compatibility. 2. Type of RAM: There are many types of RAM, such as SDRAM, DDR, DDR2, DDR3, So-Dimm, etc. Pick the right one. 3. Frequency: Your motherboard will only accept certain frequency of RAM, such as up to DDR3 1600MHz for example. Pick faster memory and you‘ll be forced to run it at a slower pace or it might not work at all. Pick slower memory and you will limit your system performance. As a general rule of thumb, higher frequency means higher performance, but other factors such as timings weight in too. 4. Voltage: Some RAM will require voltage that is above the regular standard. Make sure that your motherboard can supply that much voltage if required. Voltage increases are also commonplace with overclocking. Note that it is not recommended to use more than 1.65V on the RAM with Core i7 processors or you risk damaging your processor. 5. Timings: Timings or latencies, refer to the delay between certain commands executed by your computer memory sub-system. To keep this simple, all you need to know is that lower timings are better as they will reduce latency and increase bandwidth. 6. How much RAM do you need? That really depends on your needs, although I tend to recommend at least 2GB for any system, 4GB for a high performance system. 4GB to 6GB is a must for a gaming system if you want to run modern games. The more the better, especially considering the current low prices of RAM. 7. 32 or 64 bit? 32 bit operating systems can only address up to 4GB of memory in total, including the memory on your video card and within your CPU. If you plan on using 4GB of RAM or more, you‘ll have to use a 64-bit OS in order to be able to take advantage of all your RAM. 8. 4 x 1GB or 2 x 2GB? 2 x 2GB in this case. Two sticks are preferable to four, as it‘s easier for your motherboard or cpu memory controller to handle only two sticks. Four sticks can be a nightmare when it comes to compatibility and will also limit your RAM frequency and/or timings when it comes to overclocking 9. Warranty Some manufacturers offer a lifetime warranty. Some let you increase your voltage under warranty. RAM tend more to be faulty when you receive it/buy it then after several years, so it‘s a good idea to buy it from a vendor who allows for easy and painless RMA process. 10. Research This single word resumes it all: Research. Take some time to correctly do your research before buying your next stick(s) of RAM and things will go smoothly.
Types of ROM
Mask ROM Classic mask-programmed ROM chips are integrated circuits that physically encode the data to be stored, and thus it is impossible to change their contents after fabrication. Other types of non-volatile solid-state memory permit some degree of modification.
P-ROM Programmable read-only memory (PROM), or one-time programmable ROM (OTP), can be written to or programmed via a special device called a PROM programmer. Typically, this device uses high voltages to permanently destroy or create internal links (fuses or antifuses) within the chip. Consequently, a PROM can only be programmed once.
EP-ROM Erasable programmable read-only memory (EPROM) can be erased by exposure to strong ultraviolet light (typically for 10 minutes or longer), then rewritten with a process that again needs higher than usual voltage applied. Repeated exposure to UV light will eventually wear out an EPROM, but the endurance of most EPROM chips exceeds 1000 cycles of erasing and reprogramming. EPROM chip packages can often be identified by the prominent quartz "window" which allows UV light to enter. After programming, the window is typically covered with a label to prevent accidental erasure. Some EPROM chips are factory-erased before they are packaged, and include no window; these are effectively PROM.
EEP-ROM Electrically erasable programmable read-only memory (EEPROM) is based on a similar semiconductor structure to EPROM, but allows its entire contents (or selected banks) to be electrically erased, then rewritten electrically, so that they need not be removed from the computer (or camera, MP3 player, etc.). Writing or flashing an EEPROM is much slower (milliseconds per bit) than reading from a ROM or writing to a RAM (nanoseconds in both cases).
Electrically alterable read-only memory (EAROM) is a type of EEPROM that can be modified one bit at a time. Writing is a very slow process and again needs higher voltage (usually around 12 V) than is used for read access. EAROMs are intended for applications that require infrequent and only partial rewriting. EAROM may be used as non-volatile storage for critical system setup information; in many applications, EAROM has been supplanted by CMOS RAM supplied by mains power and backed-up with a lithium battery.
Flash ROM Flash memory (or simply flash) is a modern type of EEPROM invented in 1984. Flash memory can be erased and rewritten faster than ordinary EEPROM, and newer designs feature very high endurance (exceeding 1,000,000 cycles). Modern NAND flash makes efficient use of silicon chip area, resulting in individual ICs with a capacity as high as 32 GB as of 2007; this feature, along with its endurance and physical durability, has allowed NAND flash to replace magnetic in some applications (such as USB flash drives). Flash memory is sometimes called flash ROM or flash EEPROM when used as a replacement for older ROM types, but not in applications that take advantage of its ability to be modified quickly and frequently.
Secondary Storage Hard disk Drive CD/DVD Drive Floppy Disk Drive
A hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating discs (platters) coated with magnetic material. HDDs were introduced in 1956 as data storage for an IBM real-time transaction processing computer and were developed for use with general purpose mainframe and minicomputers. The first IBM drive, the 350 RAMAC, was approximately the size of two refrigerators and stored 5 million 6-bit characters (the equivalent of 3.75 million 8-bit bytes) on a stack of 50 discs. In 1961 IBM introduced the model 1311 disk drive, which was about the size of a washing machine and stored two million characters on a removable disk pack. Users could buy additional packs and interchange them as needed, much like reels of magnetic tape. Later models of removable pack drives, from IBM and others became the norm in most computer installations and reached capacities of 300 megabytes by the early 1980s. Non-removable HDDs were called fixed disk drives.
Basic components of a hard drive The basic components of a typical hard disk drive are as follows
PLATTERS: Platter is a circular, metal disk that is mounted inside a hard disk drive. Several platters are mounted on a fixed spindle motor to create more data storage surfaces in a smaller area. The platter has a core made up of aluminums or glass substrate, covered with a thin layer of Ferric oxide or cobalt alloy. On both sides of the substrate material, a thin coating is deposited by a special manufacturing technique. This, thin coating where actual data is stored is the media layer.
READ/WRITE HEADS: The heads are an interface between the magnetic media where the data is stored and electronic components in the hard disk. The heads convert the information, which is in the form of bits to magnetic pulses when it is to be stored on the platter and reverses the process while reading.
THE SPINDLE MOTOR: Spindle motor plays an important role in hard drive operation by turning the hard disk platters. A spindle motor must provide stable, reliable, and consistent turning power for many hours of continuous use. Many hard drive failures occur due to spindle motor not functioning properly.
HARD DISK LOGIC BOARD: Hard disk is made with an intelligent circuit board integrated into the hard disk unit. It is mounted on the bottom of the base casting exposed to the outer side. The read/write heads are linked to the logic board through a flexible ribbon cable.
DRIVE BAY: The entire hard disk is mounted in an enclosure designed to protect it from the outside air. It is necessary to keep the internal environment of the hard disk free of dust and other contaminants. These contaminants may get accumulated in the gap between the read/write heads and the platters, which usually leads to head crashes.
Types of Hard Disk Drives
Disk drive technologies have advanced quickly over recent years, making terabytes of storage available at reasonable cost. When researching the type of hard disk storage system appropriate for your needs, keep in mind the format and data rate of the video you‘re capturing. Depending on whether you work as an independent video editor or collaborate with others, the amount of storage you require and the bit rate of data transfer will be important factors to match up with your storage needs.
ATA Disk Drives There are two kinds of ATA disks: Parallel (Ultra) ATA disks: These are found in Power Mac G4 computers. Serial ATA disks: These come with Power Mac G5 computers. ATA disks do not offer as high a level of performance as LVD or Ultra160 SCSI disks. If you plan to use Ultra ATA disks, make sure that: The sustained transfer speed is 8 MB/sec. or faster The average seek time is below 9 ms The spindle speed is at least 5400 rpm, although 7200 rpm is better
Parallel (Ultra) ATA Disks Many editors use parallel ATA (PATA) disks (also called Ultra DMA, Ultra EIDE, and ATA-33/66/100/133) with DV equipment. Parallel ATA disks are disks that you install internally. Because imported DV material has a fixed data rate of approximately 3.6 MB/sec., high-performance parallel ATA disks typically can capture and output these streams without difficulty. The numbers following the ATA designation indicate the maximum data transfer rate possible for the ATA interface, not the disk drive itself. For example, an ATA-100 interface can theoretically handle 100 MB/sec., but most disk drives do not spin fast enough to reach this limit. Parallel ATA disks use 40- or 80-pin-wide ribbon cables to transfer multiple bits of data simultaneously (in parallel), they have a cable length limit of 18 inches, and they require five volts of power. Depending on your computer, there may be one or more parallel ATA (or IDE) controller chips on the motherboard. Each parallel ATA channel on a computer motherboard supports two channels, so you can connect two disk drives. However, when both disk drives are connected, they must share the data bandwidth of the connection, so the data rate can potentially be reduced.
Serial ATA Disks Serial ATA (SATA) disks are newer than parallel ATA disk drives. The disk drive mechanisms may be similar, but the interface is significantly different. The serial ATA interface has the following characteristics: Serial data transfer (one bit at a time) 150 MB/sec. theoretical data throughput limit 7-pin data connection, with cable limit of 1 meter Operates with 250 mV Only one disk drive allowed per serial ATA controller chip on a computer motherboard, so disk drives do not have to share data bandwidth
SCSI Disk Drives Small Computer System Interface (SCSI) disk drives used to be among the fastest drives available, although newer computers may no longer provide SCSI ports. Although no longer highly popular, SCSI technology has been implemented in various ways over the years, with each successive generation achieving better performance. Two fast SCSI standards for video capture and playback are: Ultra2 LVD (Low Voltage Differential) SCSI: Ultra2 LVD SCSI disk drives offer fast enough performance to capture and output video at high data rates when a single disk is formatted as a single volume (as opposed to formatting several disks together as a disk array). Ultra320 and Ultra160 SCSI: These are faster than Ultra2 LVD SCSI disks.
SCSI disks can be installed internally or connected externally. Many users prefer external SCSI disk drives because they‘re easier to move and they stay cooler. If your computer didn‘t come with a preinstalled Ultra2 LVD, Ultra160, or Ultra320 SCSI disk drive, you need to install a SCSI card in a PCI Express slot so you can connect a SCSI disk drive externally. A SCSI card allows you to connect up to 15 SCSI disk drives in a daisy chain, with each disk drive connected to the one before it and the last terminated. (Some SCSI cards support more than one channel; multiple-channel cards support 15 SCSI disks per channel.) Use high-quality, shielded cables to prevent data errors. These cables should be as short as possible (3 feet or less); longer cables can cause problems. You must use an active terminator on the last disk for reliable performance. Note: Active terminators have an indicator light that goes on when the SCSI chain is powered.
All devices on a SCSI chain run at the speed of the slowest device. To achieve a high level of performance, connect only Ultra2 or faster SCSI disk drives to your SCSI interface card. Otherwise, you may impede performance and get dropped frames during capture or playback. Note: Many kinds of SCSI devices are slower than Ultra2 devices, including scanners and removable storage media. You should not connect such devices to your high-performance SCSI interface.
External removable HDD This is the hard disk drives external to system typically connect via USB cable. It is removable in nature and features large storage options and portable design. It can be use for: • Backup • Data storage • External boot disk for system • Data cloning/recovery
Hard Disk Drive Interfaces There are a few ways in which a hard disk can connect/interface with:
ATA (IDE, ATAPI, PATA) IDE (ATA-1): This is the original definition which allowed for two devices on each adapter, one assigned as a master (device 0) and the other as a slave (device 1). The devices themselves had to have some mechanism, usually a jumper, to determine which was which. The interface used DMA which allowed devices to transfer data directly to memory without requiring processor intercession. The interface allowed for data transfer rates up to 4.16 Megabytes per second. EIDE (ATA-2): EIDE increased performance over IDE by increasing the total hard drive size supported to 137.4 Gigabytes and increasing the maximum data transfer rate to 16.67 Megabytes per second. BIOS limitations, however, limited drive size to 8.4 Gigabytes. ATA-3: ATA-3 provided for improved reliability and password protection to access drives. ATA-4: ATA-4 used better DMA support and integration of AT Attachment Program Interface (ATAPI) which provides a common interface for CDROMs. The interface allowed for data transfer rates up to 33.33 Megabytes per second. ATA-4 also defined the use of 80 conductor cables where alternating wires in the cable are connected to ground in order to reduce the effects of electrical interference. ATA-5: ATA-5 added auto detection for the cable type and increased data transfer rates (up to 66.67 Megabytes per second).
SATA A brief description of the changes in the SATA interface is presented below. The original SATA definition allowed for a data transfer rate of 1.5 gigabits per second (Gbit/s). This generation of SATA was not noticeably faster than the last generation of ATA devices. The second generation of SATA allows multiple device transactions to occur simultaneously in addition to increasing the bit rate to 3.0 Gbit/s. Because of the faster data rate, 3.0 Gbit/s SATA requires a cable that is capable of supporting the higher rate. (1.5 Gbit/s cables will work, just not for high demand applications.) 6.0 Gbit/s SATA exists, but for the most part, this data rate far exceeds that which today's hard drives are capable of driving.
SATA Speed in Year Version Both Directions Intro
SATA I 1.5 Gbps 2002 SATA II 3.0 Gbps 2003 SATA III 6.0 Gbps 2008
SCSI SCSI is commonly used in servers, and more in industrial applications than home uses.
Disadvantages Costs Not widely supported Many, many different kinds of SCSI interfaces SCSI drives have a higher RPM, creating more noise and heat
Advantages Faster Wide range of applications Better scalability and flexibility in Arrays (RAID) Backward compatible with older SCSI devices Better for storing and moving large amounts of data Tailor made for 24/7 operations Reliability Partitioning and Formatting Hard Drives Physical hard drives and logical hard drives are two different things. Just because you have one physical hard drive mounted in your PC doesn't mean that you couldn't have more than one hard drive designation. For example, when you look at Windows Explorer, you might see multiple drives listed as C:, D:, E:, etc. even though you may only have a single drive installed in the machine. Back in the old days, the largest hard drive that the Microsoft Disk Operating System (DOS) could recognize was 85 Megabytes. Not much, huh? So when larger hard drives came out, we needed to have a way to make them accessible to the user for storing program or data files. To do this, a larger drive was divided into smaller hard drives, no one of which was bigger than 85 Meg. This "dividing up" is referred to as partitioning. Still just one physical drive, but now the operating system thought it saw multiple logical drives. This division of the single physical drive was accomplished simply by storing a specific pattern of ones and zeros to the hard drive to designate the end of one partition and the beginning of another. Each partition has its own file system. There are a number of types of file systems, each of which is generally associated with a specific operating system. For example, the NTFS file system is attributed to Microsoft while the EXT3 file system is attributed to Linux. File systems are generally incompatible although some operating systems such as Linux can read and sometimes write to other operating system file systems. Partitioning Exercise The following is a step-by-step exercise allowing you to examine the partitions on the external drive you purchased for this course. 1. Begin by booting up any machine running XP and logging in as an administrator. 2. Connect your external drive to an available USB port. 3. Next, we will want to run Microsoft's Computer Management. To do this, right-click on "My Computer" in Windows Explorer and select "Manage" from the context-specific menu. Computer Management, a program that looks much like Windows Explorer, will appear with a system tree of resources in the left pane and a detailed list of the components within the selected resource in the right pane. Alternatively, you can go to the
4. Start menu and select run. A window will open prompting you to enter the name of the program you want to run. Enter "compmgmt.msc" (without the quotes) in the text field and press Enter. 5. Under the "Storage" resource in the system tree, select "Disk Management." When you do this, a list of volumes should appear in the top right pane (these are the logical drives) and a graphic of the physical disks should appear in the lower right pane.
5. In the list of physical disks in the lower right pane, identify your external hard disk. You should be able to do this by clicking on the logical drive in the upper right pane that is associated with your disk. When you click on this, the physical disk that represents this volume should become highlighted with diagonal hash marks. 6. At this point, we can create multiple partitions on your drive if you wish. If you have unpartitioned space on your hard drive, you can subdivide this region of your drive into one or more partitions. If, however, you do not have any unpartitioned space, you will have to delete a current partition in order to sub divide it. Important: be sure you understand that this step describes deleting a partition, something you should only do if you feel 100% certain that you do not need any data that is currently on the drive. Right click on the disk you want to partition, and in the context-specific menu that appears, select, "Delete Partition.
Troubleshoot hard drive failures in seven easy steps When a floppy or CD-ROM drive doesn‘t work, it‘s an annoying but not particularly scary problem to fix. However, when a hard disk fails, the computer doesn‘t boot—as in the case of a boot drive failure—and the frenzy to save important company data ensues. When faced with such a problem, don‘t panic. Just remember these simple troubleshooting tips for hard drives.
1. Physical connectivity—Is the drive receiving power? Is it plugged into the PC by a correctly connected ribbon cable? For IDE drives, are its jumpers set correctly? Or with SCSI drives, are its SCSI termination and ID set correctly? 2. BIOS setup—Does the BIOS see the drive? 3. Viruses—Does the drive contain any boot sector viruses I need to remove before continuing? 4. Partitioning—Does FDISK find a valid partition on the drive? Is it active? 5. Formatting—Is the drive formatted using a file system that the OS can recognize? 6. Drive errors—Is a physical or logical drive error causing read/write problems on the drive? 7. Operating system—Does your OS have a feature that checks the status of each drive on your system? If so, what is that status?
Checking physical connectivity To work properly, a hard drive needs power and a connection via a ribbon cable to the PC. If a drive doesn‘t work after moving it to a new PC, after physically moving the PC, or after the cover has been taken off, start your troubleshooting by checking the physical connectivity. It‘s possible for plugs to jiggle loose when moving a PC, and it‘s easy to uproot a ribbon cable connection when pulling circuit boards or performing other maintenance tasks inside the case.
A hard disk works with any Molex connector from the PC‘s power supply. Make sure the plug is fully inserted. Molex connectors require a lot of pressure to fully insert, and even more pressure to remove, so don‘t be afraid to push hard or pull, as the case may be. Just make sure you handle the plastic connector, and do not try to push or pull the wires.
As the PC starts up, place the palm of your hand on the flat part of the hard disk. If you can detect any vibration, the drive probably has power. If there‘s no movement at all, either the drive‘s physical mechanism is shot or the Molex connector you have selected is faulty. Try using a different connector before assuming the drive has a problem.
Systems like the AT/LPX have a small connector that runs from the front of the case to the hard disk. On ATX systems, it runs from the motherboard to the hard disk. This enables the LED on the case to illuminate when the hard disk is in use. Don‘t rely on that LED as a positive indicator as to whether or not the hard disk is receiving power, though. The light could be burned out, the wire disconnected, or the drive might be receiving power but not be connected correctly to the PC.
The other physical requirement for a drive is the PC itself. If it‘s an IDE model, the drive should be connected via a ribbon cable to the IDE bus on the motherboard. Connections can also be made with a SCSI or proprietary expansion card. Secure both ends of the ribbon cable connector and make sure the connector is covering all pins. On systems where the pins are bare instead of surrounded by a plastic ridge, it‘s easy to offset the connector by a row or two on the pins. If the drive is getting power but the BIOS can‘t find it, try a different ribbon cable; the one in use might have a broken wire or other flaw.
There are two types of hard disk ribbon cables: 40-wire and 80-wire. UltraDMA 66 and above requires the 80- wire cable. If you use the 40-wire type, the drive will be limited to UltraDMA 33 performance.
The red stripe on the ribbon cable must match up with Pin 1 on both the drive and the motherboard or expansion card. Sometimes, though, it‘s not easy to locate Pin 1. Look for tiny numbers at one end of the connector. If you see a 1 or 2, that‘s the end with which the red stripe should be matched. Some connectors are notched on one side while the ribbon cables have a tab that fits into that notched area. However, this isn‘t always the case. Unlike with floppy drives, where the drive light stays on even if you have the ribbon cable backward, there is no simple way to tell whether you have the cable backwards. Without the notched connectors, your only choice is to use the trial-and- error method.
Don‘t mount the drive in the computer case until you‘re sure it works. Sometimes those little screws can be hard to reach, so you only want to mount the drive once. For testing purposes, the hard disk can temporarily sit at an angle, unmounted, but propped up in some way. Don‘t allow the drive to hang suspended by the ribbon cable or power cable; this puts stress on the cable and can cause broken wires or dislocated connectors.
Checking jumper settings On an IDE hard disk, one or more jumpers on the drive must be set to determine its Master/Slave status. This setting isn‘t usually an issue in an existing hard disk installation that suddenly doesn‘t work anymore, but it can cause problems when you move a drive from one PC to another.
Depending on the drive, the following jumper settings may be available.
Single—Use this setting when the drive is the only one on that IDE subsystem; that is, the only one on that ribbon cable. Not all drives have a Single setting; if there is none, use the Master setting instead. Master (MS)—When there are two drives on the IDE subsystem and the other drive‘s jumpers are set to Slave, or if this is the only drive on the subsystem and it doesn‘t have a separate Single setting, use this setting. Slave (SL)—Use this setting when there are two drives on the IDE subsystem and the other drive‘s jumpers are set to Master. Cable Select (CS)—If you are using a cable that relies on the device positioning to determine its Slave/Master status, use this setting. This setting is uncommon.
Depending on the drive, the jumper positions may or may not be clearly labeled. There should be a chart or sticker on the drive showing the positions. If you see neither, try visiting the drive manufacturer‘s Web site to see if a diagram is available. Checking SCSI termination If the machine uses a SCSI drive, there are two factors with which to be concerned: termination and ID. These settings are not an issue when troubleshooting a drive that has suddenly gone bad in an existing system, but if you are moving a drive from one system to another and it doesn‘t work in the new system, improper SCSI settings may be the culprit.
If this is the last SCSI device in the chain, it must be terminated. Termination methods vary. On some devices, you set termination with an extra jumper; on others, you use a cap or plug over a connector. On most hard disks, you terminate using a jumper setting.
SCSI-based drives usually have jumpers just like ATAPI ones, but instead of setting the Master/Slave status, they assign a SCSI ID number to the device. Some SCSI devices have a wheel or button instead of jumpers with a little window indicating the setting, but this is uncommon on a hard disk.
There can be up to seven SCSI devices on a single narrow SCSI bus, and up to 15 devices on a wide SCSI bus. There are either eight or 16 addresses in total, depending on your system. The host adapter takes one of those addresses, leaving seven or 15 for the remaining drives. Usually, the host adapter claims the highest number for itself.
The SCSI ID comes from a binary representation of the jumpers. For example, on a device with three SCSI jumpers and all of them are without jumper settings, the ID would be 000b (b stands for binary here), or 0. An ID of 001b would be 1; 010b would be 2; and so on.
The problem lies in the fact that some manufacturers set the jumpers to read from left-to-right, while others use right-to-left. So on one drive, the leftmost jumper set would be 1, while on some other drive, the rightmost jumper set would be 1. Check the drive‘s label for information about which way the drive works. If all else fails, try the manufacturer‘s Web site.
Checking BIOS setup (IDE only) In most modern systems, the BIOS can automatically detect your hard disk, so no special BIOS setup is required. However, if you are working with an older or quirky BIOS, you might need to enter the BIOS setup program and change the drive‘s IDE channel—i.e., Primary Master, Primary Slave, etc.—from None to Auto so the BIOS will attempt to find and identify the drive.
On an old BIOS, you occasionally may need to select User as the drive type and manually enter the drive‘s settings. Automatic detection of IDE devices was part of the ATA-3 standard, released more than 10 years ago, though, doing so would be rare. To enter the BIOS setup program, watch the screen at startup. It should list the key you need to press to enter Setup. The most common ones are [Delete], [F1], or [F2].
Some BIOSs also have a separate Detect IDE Devices utility built in. If the BIOS contains such a utility, you can use it to prompt the BIOS to detect the new hard disk. This comes in handy when you aren‘t sure whether or not the drive is working, because you can get an answer immediately rather than rebooting and waiting to see whether the BIOS finds the drive on startup.
Virus checking If you‘ve come this far in the troubleshooting process and the drive still isn‘t working, check for viruses. A drive containing a boot-sector virus will not only malfunction, it can spread the virus to the disk you boot from, such as your emergency startup disk (DOS or Windows 9x/Me).
On a system that you know is good and that has an antivirus program installed, update the virus definitions, and then make a virus-checking boot disk. Write protect it, and then use it to start the system containing the nonworking hard disk and check it for errors. If the drive is not partitioned and formatted, the boot disk might not be able to check the data area of the drive. That‘s okay for now; just let it get as far as it can before moving on to the next step, checking the partition.
Checking for a valid partition If the BIOS can see the drive but the drive isn‘t working, make sure the drive is partitioned. Use FDISK, a command-line utility you‘ll find on a Windows 9x/Me startup disk, to check. Boot from the write-protected startup disk and type FDISK. When asked whether or not you want large disk support, type Y.
If you choose N when questioned about enabling large disk support, any partitions you later format on the resulting partitions will be formatted as FAT rather than FAT32.
If the active partition‘s type is FAT, FAT32, or NTFS, it should be recognized by the operating system. One exception would be if you put an NTFS drive into a Windows 9x/Me system. The OS wouldn‘t recognize the NTFS because it doesn‘t support NTFS, not because it was partitioned incorrectly.
If it is a partition problem, you have two choices: Try to recover the data using a disk recovery program, or give up on the data, delete the partition, and re-create it in FDISK. If you want to try recovery first, see the section below on Advanced Data Recovery Options.
If you want to delete the partition and re-create it, return to the FDISK main screen by pressing [Esc] and deleting the partition (option 3 on the screen), and then return to the main screen again and create a partition (option 1 on the screen). After using FDISK to create or delete partitions, you must reboot the machine before doing anything else.
Checking drive formatting If FDISK recognizes the drive and it has a valid partition type, you should be able to view the drive‘s content from a command prompt via your startup disk, or from the Recovery Console in Windows 2000 or XP. Change to that drive by typing its drive letter followed by a colon and pressing [Enter]. Then, display a list of files on the drive with the DIR command.
If you see a message about an invalid media type, the drive is probably not formatted using a file system that your OS recognizes. You can either try a data recovery program, or you can give up on the drive‘s data and reformat it with the FORMAT command.
If you booted from a Windows 9x/Me boot disk, but your system ordinarily runs Windows NT, 2000, or XP, the disk might be formatted with NTFS. The fact that the boot disk‘s OS cannot read it does not necessarily mean there is a problem with the formatting. For those OSs, try booting to the Windows Recovery Console to see whether or not you can access the disk from there.
Fixing physical and logical drive errors Let‘s assume at this point that your OS finds the drive and can read some files on it, but not all of them. Maybe you‘re receiving read or write errors, or certain programs aren‘t working right. The problem is likely a physical or logical disk error.
A physical disk error is a bad spot on the drive. It can result from physical trauma to the computer, like knocking it off of a table while it‘s running.
For many years, hard disks have been self-parking; when you shut down the PC, the read/write head on the drive moves to the parking area of the disk where no data is ever stored. Then, if the computer gets bumped
or jostled while it‘s off, and the read/write head bounces up against the drive, no data will be lost. However, while a computer is running, damage can occur from physical trauma.
A logical disk error is a discrepancy between the two copies of the file allocation table (FAT) on the disk, or a discrepancy between the FAT‘s version of what clusters are stored on the drive and the reality of actual storage. Such errors are typically caused by improperly shutting down the PC or abnormal program termination.
A message about a data error while reading or writing the drive is probably a physical error. Logical errors are manifested in many different ways, not always directly attributable to the disk itself. For example, certain programs might fail to run or might lock up after starting. Such a problem could mean a memory parity error or even a bad cooling fan; you never know until you check the system and eliminate the possibilities.
It‘s best to try the simplest solution first, so run a disk-checking program. Windows 9x/Me/2000 comes with ScanDisk, which will check for both physical and logical errors. Windows XP comes with a similar utility called Check Disk. In Windows XP, access Check Disk from the Tools tab of the drive‘s Properties sheet. In early versions of DOS, a command-line utility called CHKDSK does the same thing. Use it with the /F switch to fix any errors it finds.
With Disk Management, the most important thing to check is the status of each drive. For example, in Figure, you can see there are two hard disks: one FAT32 and one NTFS. Both are reported to be Healthy. If a drive reports that it is offline or a status other than Healthy, right-click it and choose Reactivate Disk
Advanced data recovery options There are several good data recovery programs on the market today that can help you retrieve files from a hard disk that has suffered some type of disaster..
There are many other brands of recovery software on the market; a search for data recovery software in any search engine will turn up several. You can also seek out a company that does data recovery, rather than buying the software yourself.
Conclusion Because so much is stored on hard disks these days, knowing how to revive a failed hard drive is an important function for support techs. Having an effective guide to the recovery process might mean the difference between a total loss and full recovery. With my seven-step process, though, you‘ll be ready to tackle nearly any type of hard disk error that presents itself.
Hard drive buying tips
When purchasing a hard drive, it is important to understand and verify the hard drive is suitable for your uses and has or does not have the options you may or may not need. Unfortunately, with hard drive technologies changing every day, it is can be sometimes confusing and frustrating when looking to purchase a hard drive.
Interface
When looking to purchase a hard drive the first and foremost important consideration is the Interface the hard drive uses to communicate with the computer. Below is a listing of each of the available interfaces with information how they may or may not apply to your computer.
IDE/ATAPI/ATA One of the more commonly found hard drives and used with IBM compatible computers, IDE is an easy to install and customize interface. Each IBM computer has the availability for a maximum of four IDE devices, these devices can range from hard drives to CD-ROM drives. If considering purchasing an IDE/ATAPI/ATA hard drive, verify that there are available locations for the drive to be connected to. SCSI Another commonly used interface, SCSI devices are found in Apple computers as well as some IBM computers. The SCSI interface is a faster solution when compared to IDE/ATAPI; however, in some cases, they can be more difficult to install. To install a SCSI hard drive you must have a SCSI card and an available connection on the SCSI cable connecting to the SCSI card. It is important to remember if you have a Proprietary SCSI card, such as a SCSI card included with the Iomega Jaz drive, this SCSI card may not always allow your hard drive to work. External (USB, Fire wire, or Parallel)Several external solutions are also available; these include but are not limited to USB hard drive, Fire wire hard drive and Parallel hard drive. When considering an external hard drive, it is important to look at the speed difference for transferring data to and from the hard drive. In addition, for these external drives to function properly, you must also have the available connection for the drive to be connected to.
Speed
In addition to the interface, it is also important to look at the transfer rates of the hard drive; long transfer rates can considerably slow down your computer when transferring larger files. When looking at the hard drive, look for specifications listing the RPM (Rotations Per Minute). An example of this would be a speed of 7,200 RPM.
Vendor
There used to be many hard drive vendors but now the number of major players is now down to three: Seagate, Western Digital and Toshiba. This is down from five just last year. Western Digital recently picked up Hitachi GST to jump into the number one spot. Not to be out done, Seagate has picked up Samsung's hard drive business.
Other considerations
Below is a listing of some other important considerations to look at when purchasing a computer hard drive.
Warranty How long is the warranty and what does it cover.
Support Is the technical support number a free number is it open 24 hours, 7 days a week. Included components Verify that the hard drive that you are purchasing comes with the needed components to install the drive. Hard drives included from the manufacturer will include an IDE or ATA/66-100 Cable, standard drive rails, instructions and diskette for installation.
Internal and External Transfer rates The Internal transfer rate is the rate the hard drive can take the data from the platter to the internal cache or read buffer. The External Transfer rate is the rate the hard drive can then take the data in the internal cache or read buffer to the computer memory.
S.M.A.R.T. S.M.A.R.T. is a new technology used to help warn the computer user of possible problems with the hard drive.
ATA, ATA/33, ATA/66, ATA/100 Another new and sometimes confusing interface is the ATA interface. Developed by Quantum in 1996, the Ultra ATA/33 interface allowed for computers to transfer up to 33 MB per second; later in 1998 this standard was upgraded to the ATA/66 standard with the availability of transferring up to 66 MB per second.
When purchasing an ATA/66 drive, the computer must support ATA66 as well as have an ATA/66 cable in order to support the transfer rate of 66 MB per second. If the computer does not have this cable, the drive will automatically be decreased to a transfer rate of 33 MB per second.
Price range
The price range can vary depending upon what interface the drive uses (SATA, IDE, SCSI, or USB), capacity of the drive, and the RPM (Speed) of the drive.
Floppy disk Drive
A floppy disk, or diskette, is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles. They are read and written by a floppy disk drive (FDD).
Floppy disks, initially as 8-inch (200 mm) media and later in 5.25-inch (133 mm) and 3.5-inch (90 mm) sizes, were a ubiquitous form of data storage and exchange from the mid-1970s well into the first decade of the 21st century.
History of the Floppy Disk Drive
The floppy disk drive (FDD) was invented at IBM by Alan Shugart in 1967. The first floppy drives used an 8-inch disk (later called a "diskette" as it got smaller), which evolved into the 5.25-inch disk that was used on the first IBM Personal Computer in August 1981. The 5.25-inch disk held 360 kilobytes compared to the 1.44 megabyte capacity of today's 3.5-inch diskette.
The 5.25-inch disks were dubbed "floppy" because the diskette packaging was a very flexible plastic envelope, unlike the rigid case used to hold today's 3.5-inch diskettes.
By the mid-1980s, the improved designs of the read/write heads, along with improvements in the magnetic recording media, led to the less-flexible, 3.5-inch, 1.44-megabyte (MB) capacity FDD in use today. For a few years, computers had both FDD sizes (3.5-inch and 5.25-inch). But by the mid-1990s, the 5.25-inch version had fallen out of popularity, partly because the diskette's recording surface could easily become contaminated by fingerprints through the open access area.
Floppy Disk Parts
1. Write-protect hole 2. Hub 3. Shutter 4. Shell (cover) 5. Liner sheet 6. Track 7. Sector
A floppy disk is a lot like a cassette tape:
Both use a thin plastic base material coated with iron oxide. This oxide is a ferromagnetic material, meaning that if you expose it to a magnetic field it is permanently magnetized by the field. Both can record information instantly. Both can be erased and reused many times. Both are very inexpensive and easy to use.
If you have ever used an audio cassette, you know that it has one big disadvantage -- it is a sequential device. The tape has a beginning and an end, and to move the tape to another song later in the sequence of songs on the tape you have to use the fast forward and rewind buttons to find the start of the song, since the tape heads are stationary. For a long audio cassette tape it can take a minute or two to rewind the whole tape, making it hard to find a song in the middle of the tape.
A floppy disk, like a cassette tape, is made from a thin piece of plastic coated with a magnetic material on both sides. However, it is shaped like a disk rather than a long thin ribbon. The tracks are arranged in concentric rings so that the software can jump from "file 1" to "file 19" without having to fast forward through files 2-18. The diskette spins like a record and the heads move to the correct track, providing what is known as direct access storage.
The Drive
The major parts of a FDD include:
Read/Write Heads: Located on both sides of a diskette, they move together on the same assembly. The heads are not directly opposite each other in an effort to prevent interaction between write operations on each of the two media surfaces. The same head is used for reading and writing, while a second, wider head is used for erasing a track just prior to it being written. This allows the data to be written on a wider "clean slate," without interfering with the analog data on an adjacent track. Drive Motor: A very small spindle motor engages the metal hub at the center of the diskette, spinning it at either 300 or 360 rotations per minute (RPM). Stepper Motor: This motor makes a precise number of stepped revolutions to move the read/write head assembly to the proper track position. The read/write head assembly is fastened to the stepper motor shaft. Mechanical Frame: A system of levers that opens the little protective window on the diskette to allow the read/write heads to touch the dual-sided diskette media. An external button allows the diskette to be ejected, at which point the spring-loaded protective window on the diskette closes. Circuit Board: Contains all of the electronics to handle the data read from or written to the diskette. It also controls the stepper-motor control circuits used to move the read/write heads to each track, as well as the movement of the read/write heads toward the diskette surface. Floppy Disk Sensors: 1. Index sensor: -senses the index point attached to the spindle motor 2. Track0 sensor: - senses that the head is at track0 3. Write- protect sensor: -senses whether the write-protect hole in the disk is opened or closed
The read/write heads do not touch the diskette media when the heads are traveling between tracks. Electronic optics check for the presence of an opening in the lower corner of a 3.5-inch diskette (or a notch in the side of a 5.25-inch diskette) to see if the user wants to prevent data from being written on it.
Writing Data on a Floppy Disk
The following is an overview of how a floppy disk drive writes data to a floppy disk. Reading data is very similar. Here's what happens:
1. The computer program passes an instruction to the computer hardware to write a data file on a floppy disk, which is very similar to a single platter in a hard disk drive except that it is spinning much slower, with far less capacity and slower access time. 2. The computer hardware and the floppy-disk-drive controller start the motor in the diskette drive to spin the floppy disk. The disk has many concentric tracks on each side. Each track is divided into smaller segments called sectors, like slices of a pie. 3. A second motor, called a stepper motor, rotates a worm-gear shaft (a miniature version of the worm gear in a bench-top vise) in minute increments that match the spacing between tracks. The time it takes to get to the correct track is called "access time." This stepping action (partial revolutions) of the stepper motor moves the read/write heads like the jaws of a bench-top vise. The floppy-disk-drive electronics know how many steps the motor has to turn to move the read/write heads to the correct track. 4. The read/write heads stop at the track. The read head checks the prewritten address on the formatted diskette to be sure it is using the correct side of the diskette and is at the proper track. This operation is very similar to the way a record player automatically goes to a certain groove on a vinyl record. 5. Before the data from the program is written to the diskette, an erase coil (on the same read/write head assembly) is energized to "clear" a wide, "clean slate" sector prior to writing the sector data with the write head. The erased sector is wider than the written sector -- this way, no signals from sectors in adjacent tracks will interfere with the sector in the track being written. 6. The energized write head puts data on the diskette by magnetizing minute, iron, bar-magnet particles embedded in the diskette surface, very similar to the technology used in the magnetic stripe on the back of a credit card. The magnetized particles have their north and south poles oriented in such a way that their pattern may be detected and read on a subsequent read operation. 7. The diskette stops spinning. The floppy disk drive waits for the next command.
On a typical floppy disk drive, the small indicator light stays on during all of the above operations.
Floppy Disk Drive Facts
Here are some interesting things to note about FDDs:
Two floppy disks do not get corrupted if they are stored together, due to the low level of magnetism in each one. In your PC, there is a twist in the FDD data-ribbon cable -- this twist tells the computer whether the drive is an A-drive or a B-drive. Like many household appliances, there are really no serviceable parts in today's FDDs. This is because the cost of a new drive is considerably less than the hourly rate typically charged to disassemble and repair a drive. If you wish to redisplay the data on a diskette drive after changing a diskette, you can simply tap the F5 key (in most Windows applications). In the corner of every 3.5-inch diskette, there is a small slider. If you uncover the hole by moving the slider, you have protected the data on the diskette from being written over or erased.
Floppy disks, while rarely used to distribute software (as in the past), are still used in these applications:
in some Sony digital cameras for software recovery after a system crash or a virus attack when data from one computer is needed on a second computer and the two computers are not networked in bootable diskettes used for updating the BIOS on a personal computer in high-density form, used in the popular Zip drive
CDs and DVDs are everywhere these days. Whether they are used to hold music, data or computer software, they have become the standard medium for distributing large quantities of information in a reliable package. Compact discs are so easy and cheap to produce that America Online sends out millions of them every year to entice new users. And if you have a computer and CD-R drive, you can create your own CDs, including any information you want.
Understanding the CD: Material
As discussed in How Analog and Digital Recording Works, a CD can store up to 74 minutes of music, so the total amount of digital data that must be stored on a CD is:
44,100 samples/channel/second x 2 bytes/sample x 2 channels x 74 minutes x 60 seconds/minute = 783,216,000 bytes
To fit more than 783 megabytes (MB) onto a disc only 4.8 inches (12 cm) in diameter requires that the individual bytes be very small. By examining the physical construction of a CD, you can begin to understand just how small these bytes are.
A CD is a fairly simple piece of plastic, about four one-hundredths (4/100) of an inch (1.2 mm) thick. Most of a CD consists of an injection-molded piece of clear polycarbonate plastic. During manufacturing, this plastic is impressed with microscopic bumps arranged as a single, continuous, extremely long spiral track of data. We'll return to the bumps in a moment. Once the clear piece of polycarbonate is formed, a thin, reflective aluminium layer is sputtered onto the disc, covering the bumps. Then a thin acrylic layer is sprayed over the aluminium to protect it. The label is then printed onto the acrylic. A cross section of a complete CD (not to scale) looks like this.
Understanding the CD: The Spiral
A CD has a single spiral track of data, circling from the inside of the disc to the outside. The fact that the spiral track starts at the centre means that the CD can be smaller than 4.8 inches (12 cm) if desired, and in fact there are now plastic baseball cards and business cards that you can put in a CD player. CD business cards hold about 2 MB of data before the size and shape of the card cuts off the spiral.
What the picture on the right does not even begin to impress upon you is how incredibly small the data track is -- it is approximately 0.5 microns wide, with 1.6 microns separating one track from the next. (A micron is a millionth of a meter.) And the bumps are even more miniscule
Understanding the CD: Bumps The elongated bumps that make up the track are each 0.5 microns wide, a minimum of 0.83 microns long and 125 nanometres high. (A nanometre is a billionth of a meter.) Looking through the polycarbonate layer at the bumps, they look something like this: You will often read about "pits" on a CD instead of bumps. They appear as pits on the aluminium side, but on the side the laser reads from, they are bumps. The incredibly small dimensions of the bumps make the spiral track on a CD extremely long. If you could lift the data track off a CD and stretch it out into a straight line, it would be 0.5 microns wide and almost 3.5 miles (5 km) long! To read something this small you need an incredibly precise disc-reading mechanism. Let's take a look at that.
CD player Components
The CD player has the job of finding and reading the data stored as bumps on the CD. Considering how small the bumps are, the CD player is an exceptionally precise piece of equipment. The drive consists of three fundamental components:
A drive motor spins the disc. This drive motor is precisely controlled to rotate between 200 and 500 rpm depending on which track is being read. A laser and a lens system focus in on and read the bumps. A tracking mechanism moves the laser assembly so that the laser's beam can follow the spiral track. The tracking system has to be able to move the laser at micron resolutions.
What the CD Player Does: Laser Focus
Inside the CD player, there is a good bit of computer technology involved in forming the data into understandable data blocks and sending them either to the DAC (in the case of an audio CD) or to the computer (in the case of a CD-ROM drive).
The fundamental job of the CD player is to focus the laser on the track of bumps. The laser beam passes through the polycarbonate layer, reflects off the aluminium layer and hits an opto-electronic device that detects changes in light. The bumps reflect light differently than the "lands" (the rest of the aluminium layer), and the opto-electronic sensor detects that change in reflectivity. The electronics in the drive interpret the changes in reflectivity in order to read the bits that make up the bytes.
What the CD player Does: Tracking The hardest part is keeping the laser beam centred on the data track. This centring is the job of the tracking system. The tracking system, as it plays the CD, has to continually move the laser outward. As the laser moves outward from the centre of the disc, the bumps move past the laser faster -- this happens because the linear, or tangential, speed of the bumps is equal to the radius times the speed at which the disc is revolving (rpm). Therefore, as the laser moves outward, the spindle motor must slow the speed of the CD. That way, the bumps travel past the laser at a constant speed, and the data comes off the disc at a constant rate.
CD Encoding Issues If you have a CD-R drive, and want to produce your own audio CDs or CD-ROMs, one of the great things you've got going in your favour is the fact that software can handle all the details for you. You can say to your software, "Please store these songs on this CD," or "Please store these data files on this CD-ROM," and the software will do the rest. Because of this, you don't need to know anything about CD data formatting to create your own CDs. However, CD data formatting is complex and interesting, so let's go into it anyway.
To understand how data are stored on a CD, you need to understand all of the different conditions the designers of the data encoding methodology were trying to handle. Here is a fairly complete list:
Because the laser is tracking the spiral of data using the bumps, there cannot be extended gaps where there are no bumps in the data track. To solve this problem, data is encoded using EFM (eight-fourteen modulation). In EFM, 8-bit bytes are converted to 14 bits, and it is guaranteed by EFM that some of those bits will be 1s. Because the laser wants to be able to move between songs, data needs to be encoded into the music telling the drive "where it is" on the disc. This problem is solved using what is known as sub code data. Sub code data can encode the absolute and relative position of the laser in the track, and can also encode such things as song titles. Because the laser may misread a bump, there need to be error-correcting codes to handle single-bit errors. To solve this problem, extra data bits are added that allow the drive to detect single-bit errors and correct them. Because a scratch or a speck on the CD might cause a whole packet of bytes to be misread (known as a burst error), the drive needs to be able to recover from such an event. This problem is solved by actually interleaving the data on the disc, so that it is stored non-sequentially around one of the disc's circuits. The drive actually reads data one revolution at a time, and un-interleaves the data in order to play it. If a few bytes are misread in music, the worst thing that can happen is a little fuzz during playback. When data is stored on a CD, however, any data error is catastrophic. Therefore, additional error correction codes are used when storing data on a CD-ROM.
CD Data Formats
There are several different formats used to store data on a CD, some widely used and some long-forgotten. The two most common are CD-DA (audio) and CD-ROM (computer data).
CD Types: -
CD ROM –written by a manufacturer and read only memory. -CD-R – written only once by a consumer, making these disks recordable. -CD-RW – written to and erased from 1 to approximately 25 times, making these disks rewritable. -DVD – much higher storage capacity than a CD and a different storing process.
DVD: -
DVD stands for Digital Versatile Disc, and in is a high capacity CD. In fact every DVD-ROM drive is a CD-ROM drive that is they can read CDs as well as DVDs (discs). DVD uses the same technology as CD, with the main difference being higher density. The DVD standard dramatically increases the storage capacity of CD-ROM sized discs.
• Storage capacity – 8.5 GB (one side) – 17 GB (both sides) • Uses Universal Disk Format (UDF) file system • Uses accompanying decoder card to decode MPEG-compressed video data and Dolby AC-3 compressed audio
DVD FORMATS
DVD-R: -The write once version of DVD-RW.
DVD-RW: -The rewritable version of DVD-R.
DVD-RAM: - An 'early' format, Allows simultaneous playing and recording. Incompatible with most other DVD hardware.
DVD+R: - The write once version of DVD+RW.
DVD+RW: - The rewritable version of DVD+R.
Blu-Ray: - new developmental format. Developed by Sony. HD-DVD: - A high definition format developed by Toshiba. It has a smaller capacity than Blu-Ray, similar to existing formats. Received the backing of major film studios. HD DVD
Single layer capacity is 15 GB
Dual-layer capacity of 30 GB.
Toshiba is experimenting with a triple layer providing 45GB of storage.
The HD DVD disc surface layer is 0.6 mm thick, the same as DVD.
BLU-RAY
Single layer 25 GB
Dual layer 50 GB
Under development, Four layers 100 GB
Blu-ray Disc's 0.1 mm layer.
Both formats are backwards compatible with DVDs
Both use video compression techniques: MPEG2, Video Codec 1 and H.264/MPEG-4 AVC
Optical Drive Performance Specifications Many factors in a drive can affect performance, and several specifications are involved. Typical performance figures published by manufacturers are the data transfer rate, the access time, the internal cache or buffers (if any), and the interface the drive uses. This section examines these specifications.
CD Data Transfer Rate The data transfer rate for a CD drive tells you how quickly the drive can read from the disc and transfer to the host computer. Normally, transfer rates indicate the drive's capability for reading large, sequential streams of data. Transfer speed is measured two ways. The one most commonly quoted with optical drives is the "x" speed, which is defined as a multiple of the particular standard base rate. For example, CD drives transfer at 153.6KBps according to the original standard. Drives that transfer twice that are 2x, 40 times that are 40x, and so on. DVD drives transfer at 1,385KBps at the base rate, whereas drives that are 20 times faster than that are listed as 20x. Note that because almost all faster drives feature CAV, the "x" speed usually indicated is a maximum that is seen only when reading data near the outside (end) of a disc. The speed near the beginning of the disc might be as little as half that, and of course average speeds are somewhere in the middle. With today's optical drives supporting multiple disc formats, multiple read and write specifications are given for each form of media a drive supports.
CD Drive Speed Because CDs originally were designed to record audio, the speed at which the drive reads the data had to be constant. To maintain this constant flow, CD data is recorded using a technique called constant linear velocity (CLV).
In the quest for greater performance, drive manufacturers began increasing the speeds of their drives by making them spin more quickly. A drive that spins twice as fast was called a 2x drive, one that spins four times faster was called 4x, and so on. This was fine until about the 12x point, where drives were spinning discs at rates from 2,568 rpm to 5,959 rpm to maintain a constant data rate. At higher speeds than this, it became difficult to build motors that could change speeds (spin up or down) as quickly as necessary when data was read from different parts of the disc. Because of this, most drives rated faster than 12x spin the disc at a fixed rotational, rather than linear speed. This is termed CAV because the angular velocity (or rotational speed) remains a constant.
CAV drives are also generally quieter than CLV drives because the motors don't have to try to accelerate or decelerate as quickly. A drive (such as most rewritables) that combines CLV and CAV technologies is referred to as Partial-CAV or P-CAV. Most writable drives, for example, function in CLV mode when burning the disc and in CAV mode when reading. Table 11.23 compares CLV and CAV.
Table 11.23. CLV versus CAV Technology Quick Reference CLV (Constant Linear Velocity) CAV (Constant Angular Velocity) Speed of CD Varies with data position on disc. Faster on Constant inner tracks than on outer tracks. Data transfer rate Constant Varies with data position on disc. Faster on outer tracks than on inner tracks. Average noise level Higher Lower
CD-ROM drives have been available in speeds from 1x up to 52x. Most no rewritable drives up to 12x were CLV; most drives from 16x and up are CAV. With CAV drives, the disc spins at a constant speed, so track data moves past the read laser at various speeds, depending on where the data is physically located on the CD (near the inner or outer part of the track). This also means that CAV drives read the data at the outer edge (end) of the disk more quickly than data near the centre (beginning). This allows for some misleading advertising. For example, a 12x CLV drive reads data at 1.84MBps no matter where that data is on the disc. On the other hand, a 16x CAV drive reads data at speeds up to 16x (2.46MBps) on the outer part of the disc, but it also reads at a much lower speed of only 6.9x (1.06MBps) when reading the inner part of the disc (that is the part they don't tell you). On average, this would be only 11.5x, or about 1.76MBps. In fact, the average is actually overly optimistic because discs are read from the inside (slower part) out, and an average would relate only to reading completely full discs. The real-world average could be much less than that.
Troubleshooting Optical Drives
Failure Reading Any Disc
If your drive fails to read a disc, try the following solutions:
Check for scratches on the disc data surface. Check the drive for dust and dirt; use a cleaning disc. Make sure the drive shows up as a working device in System Properties. Check the drive's power and data cables if the drive is not listed. Try a disc that you know works. Restart the computer (the magic cure-all). Remove the drive from Device Manager in Windows, and allow the system to redetect the drive.
Failure to Read CD-R/RW Discs in CD-ROM or DVD Drive
If your CD-ROM or DVD drive fails to read CD-R and CD-RW discs, keep the following in mind: Some old 1x CD-ROM drives can't read CD-R media. Replace the drive with a newer, faster, cheaper model. Many early-model DVD drives can't read CD-R, CD-RW media; check compatibility. The CD-ROM drive must be MultiRead compatible to read CD-RW because of the lower reflectivity of the media; replace the drive. If some CD-Rs but not others can be read, check the media color combination to see whether some color combinations work better than others; change the brand of media. Packet-written CD-Rs (from Adaptec DirectCD or Drag to Disc and backup programs) can't be read on MS-DOS/Windows 3.1 CD-ROM drives because of the limitations of the operating system. Sometimes older drives can't read the pits/lands created at faster speeds. Record the media at a slower speed. If you are trying to read a packet-written CD-R created with DirectCD or Drag to Disc on a CD-ROM drive, reinsert the media into the original drive, eject the media, and select the option Close to Read on Any Drive. Download and install a UDF reader compatible with the packet-writing software used to create the CD-RW on the target computer. If you are not sure how the media was created, Software Architects offers a universal UDF reader/media repair program called FixUDF! (also included as part of WriteCD-RW! Pro). WriteDVD! Pro includes the similar FixDVD! UDF reader/media repair program for DVD drives.
Failure to Read a Rewritable DVD in DVD-ROM Drive or Player
If your DVD-ROM or DVD player fails to read a rewritable DVD, try the following solutions:
Reinsert DVD-RW media into the original drive and finalize the media. Make sure you don't need to add any more data to the media if you use a first-generation (DVD-R 2x/DVD-RW 1x) drive because you must erase the entire disc to do so. You can unfinalize media written by second-generation DVD-R 4x/DVD-RW 2x drives. See your DVD-RW disc-writing software instructions or help file for details. Reinsert DVD+RW media into the original drive and change the compatibility setting to emulate DVD- ROM. See the section "DVD+RW and DVD+R," earlier in this chapter, for details. Write a single-layer disc and retry if the media is dual-layer. Most DVD-ROM drives can't read DL media. Make sure the media contains more than 521MB of data. Some drives can't read media that contains a small amount of data.
Failure to Create a Writable DVD
If you can't create a writable DVD but the drive can be used with CD-R, CD-RW, or rewritable DVD media, try the following solutions:
Make sure you are using the correct media. +R and -R media can't be interchanged unless the drive is a DVD R/RW dual-mode drive. Be sure you select the option to create a DVD project in your mastering software. Some disc-mastering software defaults to the CD-R setting. Select the correct drive as the target. If you have both rewritable DVD and rewritable CD drives on the same system, be sure to specify the rewritable DVD drive. Try a different disc. Contact the mastering software vendor for a software update.
Failure Writing to CD-RW or DVD-RW 1x Media
If you can't write to CD-RW or DVD-RW 1x media, try the following solutions:
Make sure the media is formatted. Use the format tool provided with the UDF software to prepare the media for use. If the media was formatted, verify it was formatted with the same or compatible UDF program. Different packet-writing programs support different versions of the UDF standard. I recommend you use the same UDF packet-writing software on the computers you use or use drives that support the Mount Rainier standard. Make sure the system has identified the media as CD-RW or DVD-RW. Eject and reinsert the media to force the drive to redetect it. Contact the packet-writing software vendor for a software update. Know that the disc might have been formatted with Windows XP's own limited CD-writing software (which uses the CDFS instead of UDF) instead of a UDF packet-writing program. Erase the disc with Windows XP after transferring any needed files from the media; then format it with your preferred UDF program. Contact the drive vendor for a firmware update. See "Updating the Firmware in an Optical Drive," later in this chapter.
PATA Optical Drive Runs Slowly
If your PATA drive performs poorly, consider the following items:
Check the cache size in the Performance tab of the System Properties control panel in Windows XP. Select the quad-speed setting (largest cache size). Check to see whether the drive is set as the slave to your hard disk; move the drive to the secondary controller if possible. Make sure your PIO (Programmed I/O) or UDMA mode is set correctly for your drive in the BIOS. Check the drive specs and use autodetect in BIOS for the best results. (Refer to Chapter 5, "BIOS.") Check that you are using busmastering drivers on compatible systems; install the appropriate drivers for the motherboard's chipset and the OS in use. See the section "Direct Memory Access and Ultra-DMA," earlier in this chapter. With Windows 9x, open the System Properties control panel and select the Performance tab to see whether the system is using MS-DOS Compatibility Mode for CD-ROM drive. If all ATA drives are running in this mode, see www.microsoft.com and query on "MS-DOS Compatibility Mode" for a troubleshooter. If only the CD-ROM drive is in this mode, see whether you're using CD-ROM drivers in CONFIG.SYS and AUTOEXEC.BAT. Remove the lines containing references to the CD-ROM drivers (don't actually delete the lines but instead REM them), reboot the system, and verify that your CD-ROM drive still works and that it's running in 32-bit mode. Some older drives require at least the CONFIG.SYS driver to operate.
Problems Burning Discs Using Windows Built-In Recording
Windows XP's built-in CD-writing feature works only on drives that are listed in the Windows Hardware Compatibility List of supported drives and devices (www.microsoft.com/whdc/hcl/default.mspx). To install the latest updates for Windows XP, including updates to the CD-writing feature, use Windows Update. Microsoft Knowledgebase article 320174 discusses an update to the CD-writing feature. Search the Microsoft website for other solutions.
If you are using third-party writing applications, you may prefer to disable Windows' built-in writing feature. This feature is enabled or disabled with Windows Explorer. Open the drive's properties sheet Recording tab and clear the Enable CD/DVD Recording check box to disable recording, or click the empty box to enable recording.
If you have problems writing media or using your CD or DVD drive in Windows, see Microsoft Knowledgebase article 314060 for solutions.
TIP If you are unable to create discs with Windows Vista and you have a USB flash memory drive connected to your computer, eject the flash drive and try the burn again.
Trouble Reading CD-RW Discs on CD-ROM
If you can't read CD-RW discs in your CD-ROM, try the following solutions:
Check the vendor specifications to see whether your drive is MultiRead compliant. Some are not. If your drive is MultiRead compliant, try the CD-RW disc on a known-compliant CD-ROM drive (a drive with the MultiRead feature). Insert CD-RW media back into the original drive and check it for problems with the packet-writing software program's utilities. Insert CD-RW media back into the original drive and eject the media. Use the right-click Eject command in My Computer or Windows Explorer to properly close the media. Create a writable CD or DVD to transfer data to a computer that continues to have problems reading rewritable media.
Trouble Reading CD-R Discs on DVD Drive
If your DVD drive can't read a CD-R disc, check to see that the drive is MultiRead2 compliant because noncompliant DVDs can't read CD-R media. All current DVD drives support reading CD-R media.
Trouble Making Bootable Discs
If you are having problems creating a bootable disc, try these possible solutions:
Check the contents of the bootable floppy disk from which you copied the boot image. To access the entire contents of a disc, a bootable floppy must contain CD-ROM drivers, AUTOEXEC.BAT, and CONFIG.SYS. Use the ISO 9660 format. Don't use the Joliet format because it is for long-filename CDs and can't boot. Check your system's BIOS for boot compliance and boot order; the optical drive should be listed first.
Trouble Reading BD Media or Viewing BD Movies
If you are having problems reading BD media, check the following:
You must have a codec for BD (Blu-ray) media installed. These codecs are not included in Windows, but might be provided by BD drive vendors or by BD movie playback and creation programs. Clean the data side of your BD disc. See the next section, "Caring for Optical Media," for details.
If you are able to read BD media, but can't play back BD movies, check the following:
Replace drivers for your BD drive and video card. In most cases, newer drivers are better. Note that sometimes you might need to use older drivers than those installed for better results. Switch to a different BD media playback program. Use a trial version if available before purchasing a different program to assure compatibility.
Caring for Optical Media
Some people believe that optical discs and drives are indestructible compared to their magnetic counterparts. Although optical discs are more reliable than the now-obsolete floppy disks, modern optical discs are far less reliable than modern hard drives. Reliability is the bane of any removable media, and optical discs are no exceptions.
By far the most common causes of problems with optical discs and drives are scratches, dirt, and other contamination. Small scratches or fingerprints on the bottom of the disc should not affect performance because the laser focuses on a point inside the actual disc, but dirt or deep scratches can interfere with reading a disc.
To remedy this type of problem, you can clean the recording surface of the disc with a soft cloth, but be careful not to scratch the surface in the process. The best technique is to wipe the disc in a radial fashion, using strokes that start from the center of the disc and emanate toward the outer edge. This way, any scratches will be perpendicular to the tracks rather than parallel to them, minimizing the interference they might cause. You can use any type of solution on the cloth to clean the disc, so long as it will not damage plastic. Most window cleaners are excellent at removing fingerprints and other dirt from the disc and don't damage the plastic surface.
If your disc has deep scratches, you can often buff or polish them out. A commercial plastic cleaner such as that sold in auto parts stores for cleaning plastic instrument cluster and tail-lamp lenses is good for removing these types of scratches. This type of plastic polish or cleaner has a mild abrasive that polishes scratches out of a plastic surface. Products labeled as cleaners usually are designed for more serious scratches, whereas those labeled as polishes are usually milder and work well as a final buff after using the cleaner. Try using the polish alone if the surface is not scratched deeply. You can use the SkipDR device made by Digital Innovations to make the polishing job easier.
Most people are careful about the bottom of the disc because that is where the laser reads, but at least for CDs, the top is actually more fragile! This is because the lacquer coating on top of a CD is thin, normally only 6–7 microns (0.24–0.28 thousandths of an inch). If you write on a CD with a ball point pen, for example, you will press through the lacquer layer and damage the reflective layer underneath, ruining the disc. Also, certain types of markers have solvents that can eat through the lacquer and damage the disc. You should write on discs only with felt tip pens that have compatible inks, such as the Sharpie and Staedtler Lumocolor brands, or other markers specifically sold for writing on discs, such as Maxell's DiscWriter pens. In any case, remember that scratches or dents on the top of the disc are more fatal than those on the bottom. It's also important to keep in mind that many household chemicals (and even certain beverages), if spilled on an optical disc, can damage the coating and cause the material to crack or flake off. This, of course, renders the media useless.
Read errors can also occur when dust accumulates on the read lens of your drive. You can try to clean out the drive and lens with a blast of "canned air" or by using a drive cleaner (which you can purchase at most stores that sell audio CDs).
If you are having problems reading media with an older drive and firmware upgrades are not available or did not solve the problem, consider replacing the drive. With new high-speed drives with read/write support available for well under $50, it does not make sense to spend any time messing with an older drive that is having problems. In almost every case, it is more cost-effective to upgrade to a new drive (which won't have these problems and will likely be much faster) instead.
If you have problems reading a particular brand or type of disk in some drives but not others, you might have a poor drive/media match. Use the media types and brands recommended by the drive vendor.
If you are having problems with only one particular disc and not the drive in general, you might find that your difficulties are in fact caused by a defective disc. See whether you can exchange the disc for another to determine whether that is indeed the cause.