Hardware Again?

Vocabulary to learn: Bus – a connection which connects two or more devices - on a motherboard is not seen as wires in most cases as it is built into the circuit board

BIOS – basic input / output system - firmware (hardware coding) that specifies the system basic components and addressing to allow a system to start operating

Serial port – a physical interface through which information is transferred one bit at a time – has a RS-232 standard connector – not as prevalent in use since the introduction of USB devices.

Parallel port – often a printer port; originally was unidirectional data transfer. It allowed for data to be over multiple channels at the same time. Later, the standard was enhanced to be used for multiple peripherals that allowed for data to be transmitted and received at the same time.

USB –

Universal serial bus – an industry standard developed to standardize the connection between peripheral devices. Initially (Version 1.0) only had a maximum capability of 12 Mbit/s. Version 2.0 increased its speed to 480 Mbit/s (60 MB/s) and included support to charge other peripherals. Version 3.0 has speeds at 625MB/s

FSB – front side bus is a bus incorporated in the 1990s and 2000s that carries data from the CPU to a memory controller hub known as the northbridge.

Cache – a cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. It is used to speed up the computer access to instructions and data. PCI – peripheral component interconnect - is a bus for connecting peripheral devices usually by use of the expansion slot (phased out by PCIe (express) a 32-bit bus in 2004)

AGP – Accelerated graphics port – high speed connection to connect a video card to the motherboard (phased out by PCIe (express) a 32-bit bus in 2004)

IEEE 1394 Interface – “FireWire” developed by Apple, a serial bus system commonly used to connect digital cameras and other storage devices. FireWire has an edge over USB in terms of power distribution, reliability and data transfer speed.

Motherboard  The central printed circuit board (PCB) in many computer holding many of the crucial components for the system and the connectors (and ports) for peripherals (Also known as main board, system board or a logic board)

Usually includes the following: (based on a Intel design) o Socket for a microprocessor (CPU) (either with an additional PCB that houses the CPU or the CPU is surface mounted on the motherboard) o Slots for systems main memory (RAM) (presently they are called DIMM modules the newest being called DDR3 / DDR4) o Northbridge ( a chip which connects to a front side bus (FSB) leading to the CPU and then connects to main memory and peripheral buses) o ROM (usually Flash ROM) that contains the systems firmware (basic operations and communications) or BIOS o A clock generator to produce a signal to synchronize the components in the computer (stops confusion) o Slots for expansion cards o Power connectors which take power from the power supply and distribute the power to the other components connected to the motherboard (expansion cards etc) o Ports/ connectors to PS/2 mouse and keyboard o Heat sinks and mounting points for fans to disperse heat from the CPU SI or metric prefixes

Memory Addressing

Memory addresses usually address a byte of memory, by looking at the powers of two below you can see why a northbridge was integrated before the computer architecture was changed to 64-bit bus.

28 = 256 bytes of addressable memory (Each memory location a byte in length) 216 = 65,536 = 65 kB (kilobytes) 232 = 4,294,967,296 = 4 GB (Gigabyte) (a billion) Tera is 1000 billion 264 = 1.84467 x 1019 bytes = 18 EB (exabites) - Presently considered unlimited.

Speed

Computer Processor speed is measured in MHz, this is Mega-Hertz – which means millions of cycles per second. The speed is really the speed of the clock driving the computer’s processor. All computers use a timing clock, actually a crystal, to drive them. The clock alternates between high and low voltage changes, each time there is a change the computer’s processor processes some part of an instruction.

A computer that has a 500MHz clock is doing something 500 million times per second. A 1 GHz computer does something 1 billion times per second.

Comparing speeds of processors can get tricky. With similar processors, it is fairly straight forward, however if you are to compare different brands, what you are comparing each cycle can be different.

For example: Old computers would require as much as 4 cycles to do a single instruction whereas new computers can do those same instructions in one or two cycles. This was seen in the Intel processors where an 80286 was able to double the amount of work that an 8086 could do and it also ran at faster clock speeds. Different processors though can cause more differences, PowerPC processors used in the iMacs run at slower clock speeds than Intel processors, but they do more per instruction.

For a true comparison, the same application should be run on the computers of interest to determine which has the faster processing speed. Many computer magazines do such comparisons and can often be found online.