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Unit I - ( fundamentals)

Computer:

Computer is an electronic device which manipulates the according to the list of instructions. A computer is used as a data which converts data into .

Computers can solve highly complicated problems quickly and accurately. They can perform a lot of tasks such as online reservations, playing games, controlling flight timings, traffic and weather forecasting etc.

Computerization has been done in business, banking, electronic publishing, , creative designing, fashion designing etc.

Data and Information:

Data: In terms of , data means raw facts and figures.

For example, +,2,4,6,=, etc.

Whereas Information is the meaningful content which is extracted from data i.e., raw facts and figures.

For example, 2+4 = 6 here, 6 is the information.

Evolutions/History of computers:

Evolution of computers refers to the historical developments through which computers and have passed, from the time they started to exist(in ancient forms) to their current .

1. ABACUS

Many centuries ago when man started to count the numbers, he thought of a device which can trace the numbers and thus came the existence of ABACUS. It was the first counting device which was developed in China more than 3000 years ago. The name Abacus was obtained from Greek word Abax which means slab. This device basically consists of a rectangular wooden frame and beads.

2. Napier ’s Bones It is a device which contains a set of rods made of bones. It was developed by John Napier, a Scottish Mathematician and hence the device was named as Napier’s Bones. The device was mainly developed for performing multiplication and division. Later in 1614 he also introduced logarithms.

3. Pascaline Pascaline is a calculating developed by Blaise Pascal, a French Mathematician. It was the first device with an ability to perform additions and subtractions on whole numbers. The devices made up of interlocked cog wheels which contains numbers 0 to 9 on

1 its circumference. When one wheel completes its rotation the other wheel moves by one segment.

4. Babbage’s Difference and

Charles Babbage was an English mathematician. In 1822, he designed a machine called difference engine. This machine was used to calculate and print mathematical tables. The analytical engine was capable of performing all four arithmetic operations as well as comparison. It is also called pioneer computer. Hence, is rightly known as the Father of computer.

5. System Punched Card System is used for storing and retrieving data. This was invented by , an American Statistician in US Census Bureau. The system stores the data coded in the form of punched holes.

6. Mark-1

In 1943, Prof. Howard Aiken of U.S.A. constructed an electro-mechanical computer named Mark-1 which could multiply two 10 digit number in 5 second- a record at that time. This was the first operational general purpose computer.

Generations of computer:

First Generation(1940-1956) The computers in this generations were very large in and their programming was a difficult task. Examples are ENIAC, EDVAC etc. Characteristics of First generation computers: i. was core element. ii. Punched card and tape were secondary memory. iii. Generate considerable heat and poor reliability. iv. High electricity consumption v. Machine and symbolic language programming.

Second Generations(1956-1963): In this generation, the transistor was invented in 1947, and the vacuum tubes was replaced by the transistor. Transistor helped computers to become smaller, faster, cheaper, more energy- efficient and more reliable than their first-generation predecessors. Examples are IBM- 700, ATLAS etc. Characteristics of Second generation computers: i. Transistor circuit used as core element. ii. Magnetic core primary storage. iii. Required less power to operate and more reliable. iv. Computers programmed in assembly and machine languages. v. Smaller compared to first generation.

2 Third Generation(1964-1971): The third generation of computers is marked by the use of Integrated Circuits(ICs) in place of transistors. A single IC has many transistors, resistors and capacitors along with the associated circuitry. Examples include IBM/360/370, NCR 395 etc. Characteristics of Third generation computers: i. Increased miniaturization, speed and reliability. ii. Development of minicomputer. iii. Magnetic disk secondary storage. iv. Better storage devices(tapes).

Fourth Generations(1972-present): Large Scale Integrated(LSI) Circuits and Very Large Scale Integrated(VLSI) circuits were emerged in the fourth generation of computers. These circuits are packed about thousands of transistors in a single chip. Examples include 4004. Characteristics of Fourth generation computers: i. One advancement was the development of personal computers through which costs came down rapidly. Floppy disks served as a low cost, high capacity . ii. Higher storage device than earlier generations. iii. Development of or . iv. More speed than earlier generations.

Fifth Generation(Present and Beyond): In the fifth generation, the VLSI technology became ULSI(Ultra Large Scale Integration) technology resulting in the production of chips having ten million electronic components. This generation is based on parallel processing hardware and superconductor, which help to make a reality. All the higher level languages like and C++ are used in this generation. Characteristics of Fifth generation computers: i. Organic chips ii. Decreasing cost of and hardware. iii. Large facility. iv. Artificial intelligence. v. High speed processing.

Functional unit of computer:

The organizations of a computer system includes four major functional units CPU, Input unit, Output unit and storage devices.

The diagram of basic computer system is shown below:

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CPU ()

Input Unit Output Unit CU ()

ALU ()

Primary Storage

Secondary Storage Basic organization of computer system

A) Input Unit:

The following functions are performed by an input unit:

i) It accepts (or reads) the instructions and data from the outside world. ii) It converts these instructions and data in computer acceptable form because a computer can understand only binary symbols(i.e. 0 and 1) iii) It supplies the converted instructions and data to the computer system for further processing.

B) Output Unit:

The following functions are performed by an output unit:

i) It accepts the results produced by the computer, which are in coded form(i.e., in binary form), and hence , cannot be easily understood by us. ii) It converts these coded results to human acceptable(readable) form. iii) It supplies the converted result to the outside world.

C) Storage Unit:

The following functions of the storage unit are to hold:

i) The data and instruction required for processing , received from input devices. ii) Intermediate results of processing. 4 iii) Final results of processing, before these results are released to an .

The storage unit of all computers is comprised of the following two types of storage:

1. Primary storage 2. Secondary storage

D) Central Processing Unit(CPU):

Sometimes CPU is only referred to as the central processor, but more commonly called only processor, the CPU is the brain of the computer where all or most of the calculations take place. In terms of power, the CPU is the most important element of a computer system.

Two typical components of a CPU are the following:

i) The Arithmetic Logic Unit(ALU), performs arithmetic and logical operations. ii) The Control Unit(CU), extracts instructions from memory and decodes then executes them. a) Arithmetic Control Unit(ALU):

The ALU of a computer system is the place, where the actual execution of the instructions takes place, during the processing operation. To be more precise, all the arithmetic(+, -, x, /) and logical(<, >, ==, <=, >=) operations are performed in ALU.

b) Control Unit(CU):

It does not perform any actual processing on the data, the control unit acts as a central nervous system, for the other components of the computer system. It manages and co-ordinates the entire computer system. Also, it controls and guides the operations like a supervisor. It obtains instructions from the program stored in main memory, interprets the instructions and issue signals which cause other units of the system to execute them.

There are input devices are explained as under:

1. Keyboard: A computer keyboard is one of the primary input devices used with a computer. Similar to an electric typewriter, a keyboard is composed of buttons that create letters, numbers, and symbols, as well as perform other functions. 2. Mouse: A is a handheld hardware that controls a cursor in a GUI (graphical user ) and can move and select text, icons, files, and folders on your computer. 3. Scanner: A scanner is an input device that scans documents such as photographs and pages of text. When a document is scanned, it is converted into a digital format. This creates an electronic version of the document that can be viewed and edited on a computer. 4. reader: Customers new to barcoding typically ask, "What is a barcode scanner?" The answer is simple: A barcode scanner—also known as a barcode reader— is an electronic device that decodes and physically captures information contained

5 in . It consists of the following components, which work together to collect the data contained in a printed barcode:

• Light source – Illuminates the barcode for proper .

• Lens – Scans the barcode image.

• Photo conductor – Translates optical impulses into electrical ones.

• Decoder – Analyzes the data and sends the content to the scanner’s output port. A decoder can be internal or external.

There are output devices are explained as under:

1. Monitor: The term "monitor" is often used synonymously with "computer screen" or "display." The monitor displays the computer's and open programs, allowing the user to interact with the computer, typically using the keyboard and mouse. 2. : A printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. Printers vary in size, speed, sophistication, and cost. In general, more expensive printers are used for higher-resolution color printing.

Concept of Memory: , often called storage or memory, refers to computer components, devices and recording media that retain digital data used for computing in binary form. It is one of the fundamental components of all modern computers and is coupled with a Central Processing Unit(CPU). The term memory usually refers to a form of storage known as Memory(RAM) and sometimes other forms of fast but temporary storage. Similarly, the word storage refers to optical discs, forms of like hard disks and other types which are slower than RAM but of a more permanent nature. Historically, memory and storage were respectively called primary storage and secondary storage.

Memory Units: Computer stores and processes the data and information in format. A binary number is in the form of ‘0’ or ‘1’ where ‘0’ presents OFF or low voltage and ‘1’ represents ON or high voltage. The elementary unit of memory is a . The stored data in the computer is measured using some unit. Some memory units are given below: i. Bit: It stands for binary digit, which is either 0 or 1. A bit is the smallest unit of data in a computer. ii. Nibble: A nibble is a collection of 4 .

6 iii. (B): A group of 8 bits is called a byte. It is the smallest addressable data item in the computer because it is approximately one (letter ‘a’, number ‘1’, symbol ‘?’ etc). iv. (KB): In memory, a group of 1024 is called a kilobyte(KB). v. (MB): In memory, a group of 1024 KB is called a Megabyte. It is sometimes used, less precisely, to mean 1 million bytes or 1000 KB. vi. (GB): In memory, a group of 1024 MB is called a Gigabyte. It is sometimes used, less precisely, to mean 1 billion bytes or 1000 MB. vii. Terabyte(TB): In memory, a group of 1024 is called a Terabyte. It is sometimes used, less precisely, to mean 1 trillion bytes or 1000 GB. viii. Petabyte(PB): 1 Petabyte equals to 1024 terabyte. It is sometimes used, less precisely, to mean 1000 TB.

Classification of : Computer memory mainly classified into two categories shown below:

MEMORY

Primary Memory Secondary Memory

RAM ROM Magnetic Storage

SRAM DRAM PROM EPROM EEPROM Floppy Hard Magnetic Compact DVD Disk Disk Tape Disk

Primary Memory: It is the internal storage memory unit used by a computer system to hold data and instructions. It is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required. It is also known as main memory. There are two types of primary memory: 1. RAM 2. ROM 1. Random Access Memory(RAM): It is the internal memory that can be read from as well as written to. It is an that enables you to access the stored data in a random fashion, that is any byte of memory can be accessed without accessing the preceding bytes. It is volatile in nature i.e., requires power supply for the movement of current information. If power supply is interrupted, data is lost. RAM is also used in printers and other devices to improve their efficiency. Advantages of RAM: i. RAM operation is completely silent, these have no moving part. ii. Uses less power than hard drives. iii. Fastest storage medium. 7 Disadvantages of RAM: i. Volatile in nature. ii. Limited space.

2. Read Only Memory(ROM): In this type of memory, information once stored remain fixed, i.e., it cannot be changed. So, ROM can only be used for reading. It contains a set of start-up instructions, i.e., what to do a computer is turned ON. The contents on ROM remain stored even if power is turned OFF. This memory is often associated with non-volatile type of memory. Advantages of ROM: i. Non-volatile in nature. ii. Design can be easily changed or modified. iii. Cheaper and more reliable than RAMs. iv. Its contents cannot be accidentally changed. Disadvantages of ROM: i. More power consumption. ii. Data is physically encoded in circuit, so it can only be programmed during fabrication.

3. Memory: Cache is a reserved section of RAM that temporarily stores frequently used instructions and data for quick processing by the central processor of a computer. Cache memory is built into a computer’s CPU or located next to it on a separate chip. It is very nearest to the CPU and all the recent instructions are stored in it.

Characteristics of Cache Memory: i. Cache memory is faster than main memory. ii. It stores the program that can be executed within a short period of time. iii. It stores data for temporary use. iv. Cache memory has limited capacity. v. It is very expensive.

Secondary Memory: Secondary memory is also known as secondary storage or auxiliary memory. Unlike primary memory, secondary memory is used to store large amount of data permanently. It is the slower and cheaper form of memory. CPU does not access the secondary memory directly. It is a permanent storage device and non-volatile in nature, i.e., the information cannot be erased even power is switched OFF ad data will not be destructed until or unless the user erases it.

8 1. : Hard disk drive or HDD is a non-volatile, random access digital storage device. It is used for storing and retrieving digital information. All programs of a computer are installed in hard disk. Advantages: i. Huge storage capacity. ii. Stores and retrieves data much faster than a . iii. Cheap on a cost per megabyte compared to other storage media. iv. Usually fixed inside the computer so do not get lost or damaged easily. Disadvantages: i. Slower than RAM and ROM. ii. Cannot easily be transferred to another computer.

2. Compact Disk(CD): CD is an optical media that is used for electronically recording, storing and playing back audio, video, text and other information in digital form. It is relatively cheap, small, portable and round in shape storage medium which is made up of molded . The diameter the CD ranges from 10 cms to 30 cms. One CD can store 600 MB to 750 MB. Advantages: i. CDs are generally safe from computer viruses. ii. Most computers can read CDs, if there is no CD drive, a DVD drive can usually read them. iii. Small and portable. iv. Very cheap as compared to hard disk drive. Disadvantages: i. Have high data access time. ii. Can be easily broken.

3. Disk(DVD): DVD is also known as Super density Disc(SDD) or Digital Versatile Disk(DVD). A DVD is an optical media manufactured by Philips, Sony, Toshiba in 1995. offer higher storage capacity than compact disks while having the same dimension. It has capacity of 4.7 GB to 8.5 GB. Advantages: i. Superior data storage. ii. High density. iii. Portability. iv. Sound and picture quality is excellent, making them ideal for storing films with video and sound. Disadvantages: i. DVDs do not work in CD drives. ii. They can be easily damaged by breaking or scratching.

9 4. Pen/Flash/Thumb Drive: A pen drive is a data storage device that consists of (USB memory/key memory) with an integrated Universal Serial (USB) interface.USB flash drives are typically removable, rewritable and physically much smaller than a hard disk. A pen drive is a portable drive that is same as the size of your thumb that connects to the computer USB port. Today, pen drives are available in various storage capacities as 256 MB, 512 MB, 1 GB, 8 GB etc. They are widely used as an easy and small medium to transfer and store the information from their computer.

Concept of PROM, EPROM and EEPROM:

1. PROM:- (programmable read-only memory) is a memory chip on which data can be written only once. Once a program has been written onto a PROM, it remains there forever. Unlike main memory, PROMs retain their contents when the computer is turned off. 2. EPROM - (erasable programmable read-only memory) is a special type of PROM that can be erased by exposing it to ultraviolet light. Once it is erased, it can be reprogrammed. An EEPROM is similar to a PROM, but requires only electricity to be erased. 3. EEPROM - (electrically erasable programmable read-only memory). Pronounced e- e-prom, an EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM.

Characteristics of computers(Advantages):

The main characteristics of computers which have made them very useful are given below:

i) Speed: The speed of a computer is much faster than that of human beings. A powerful computer is capable of performing (10 to 40 million approx) arithmetic calculations in a second. ii) Accuracy: Computer provides a high degree of accuracy. The accuracy obtained from calculations depends on using bug-free computer chips as well as the quality of the input. iii) Storage capacity: The storage capacity of a computer is very high. Computers can store a huge amount of data in a very small space. iv) Reliability: Computers are highly consistent as compared to human beings. These are immune to tiredness and boredom or fatigue. v) Flexibility: Unlike televisions, refrigerators or typewriters, computers can do various tasks. Computers can perform repetitive jobs efficiently.

Limitations of computer(Disadvantages):

10 The limitations of computers are given below:

i) Reliability of programs: A user gives the instructions to computer to do some specific tasks, but if the instructions are not designed properly, then the task will not be performed correctly. ii) No thinking power: Computer has no capability of thinking to take a correct decision as a human being.

Concept of :

Booting is the of restarting a computer or its software. It starts with switching on of the computer and ends when the operating system is loaded in main memory and the computer is ready to take commands from the user.

The word ‘boot’ comes from ‘bootstrap’, since bootstrap helps you to get your boots on; likewise booting the computer helps it to get its Read Only Memory(ROM) instruction loaded in its main memory.

Types of booting:

It is of two types:

Cold booting: When the computer is started after having switched OFF.

Warm booting: When the operating system alone is restarted(without being switched OFF) after a system crash or ‘freeze’. Both types of booting clear out the bugs, memory conflicts and other idiosyncrasies of the operating system.

What is register(Questions on 2018-19)? A (CPU register) is one of a small set of data holding places that are part of the computer processor. A register may hold an instruction, a storage address, or any kind of data (such as a bit sequence or individual characters). Some instructions specify registers as part of the instruction.

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