COMPUTER HARDWARE

In this section, we would cover some essential of computer hardware. We would start from very basic and goes to some advanced topics. These topics would be very handy for you to locate the problem in computer hardware. You must have some basic skills in computer hardware even if you are preparing for a network administrator job.

Computer hardware refers to objects that you can actually touch, like disks, disk drives, display screens, keyboards, printers, boards, and chips. In contrast, software is untouchable. Software exists as ideas, application, concepts, and symbols, but it has no substance. A combination of hardware and software forms a usable computing system. Computer hardware is the collection of physical elements that comprise a computer system. Computer hardware refers to the physical parts or components of a computer such as a monitor, keyboard, hard disk, mouse, etc.

Computer hardware review and definition

A network administrator must be familiar with basic computer hardware operations. He should have adequate knowledge of computer hardware to perform day by day task. So in this article, we would cover some basic computer hardware terms. This could also be helpful for the interview.

What is a Computer?

· An electronic machine that can be programmed to accept data (input), and process it into useful information (output).

Kept in secondary storage (storage) for safekeeping or later use.
The processing of input into output is directed by the software but performed by the hardware.

The System Unit

The System Unit houses the central processing unit, memory modules, expansion slots, and electronic circuitry as well as expansion cards that are all attached to the motherboard; along with disk drives, a fan or fans to keep it cool, and the power supply.

All other devices (monitor, keyboard, mouse, etc., are linked either directly or indirectly into the system unit.)

The Motherboard

The motherboard is the main circuit board of a computer. It contains the central processing unit (CPU), the Basic Input/Output System (BIOS), memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers for standard peripheral devices like the keyboard, disk drive, and display screen.

The chipset is a critical part of any computer because it plays a big role in determining what sorts of features the computer can support.

Hardware components

Input devices: accept data or commands in a form useable by computers
Output devices: display processed information - printers, monitors, speakers.
Processing devices: In a system unit and are comprised of circuitry.
Storage devices: Drives read from and write to storage media (the physical material that can store data and programs).
Communication devices: provide connections between computers and communication networks, allowing for an exchange of information and data with other computers via transmission media such as cables, telephone lines, and satellites

Basic computer hardware terminology

The Motherboard

The chipset and other motherboard circuitry are the "smarts" of the motherboard. Their job is to direct traffic and control the flow of information inside the computer.

The chipset is a critical part of any computer because it plays a big role in determining what sorts of features the computer can support.

BIOS

· BIOS stands for Basic Input/Output System.
· lowest-level software in the computer
· Acts as an interface between the hardware (especially the chipset and processor) and the operating system.

· The BIOS provides access to the system hardware and enables the creation of the higher-level operating systems that you use to run your applications.
· The BIOS is also responsible for allowing you to control your computer's hardware settings, for booting up the machine when you turn on the power or hit the reset button, and various other system functions.

ROM: Read Only Memory

· ROM is nonvolatile. ROM chips contain permanently written data, called firmware (your BIOS lives here).
· ROM contains the programs that direct the computer to load the operating system and related files when the computer is powered on.
· ROM chips are usually recorded when they are manufactured.
PROM -Programmable Read Only memory chip cannot be changed to update or revise the program inside
EPROM Erasable Programmable Read Only memory Data can be erased and the chip can be reused Can be erased by shining high-intensity UV light through the window
EEPROM Electrical Erasable Programmable Read Only memory under high voltage
FROM -Flash ROM is reprogrammable memory using normal voltage inside the PC- You can upgrade the logic capabilities by simply downloading new software. This saves the expense of replacing circuit boards and chips.

Processing Devices

Cache

Pronounced cash.

It is a small, high-speed memory area that is placed between the processor and the system memory.

The value of the cache is that it is much faster than normal system memory.

The most frequently used instructions are kept in cache memory so that the CPU can look in there first - allows the CPU to run faster because it doesn't have to take time to swap instructions in and out of main memory.

Large, complex programs such as complex spreadsheets or database management programs benefit the most from having a cache memory available. Pentium II processors generally come with at least 512 KB of cache memory.

Random Access Memory (RAM)

· RAM is Primary Storage, also called internal storage.
· Serves as computers workspace, storing all or part of the program that is being executed, as well as data being used by the program.
· RAM provides instructions and data to the CPU.
· These instructions/data are coded in bytes.
· Each byte is placed in a precise location in memory, called an address.
· To access data or instructions in memory, the computer references the addresses containing the bytes.
· The amount of memory available is therefore measured in bytes
RAM chips consist of millions of switches that are sensitive to changes in electric current.
· RAM chips are typically packaged on small circuit boards called memory modules, which are inserted into special slots on the motherboard.
· RAM is Volatile storage: Power goes, data goes!
· Data/instructions are copied into memory as needed.
· Not enough memory or corruption of data/instructions in memory can cause a crash.
· On booting, operating system files are loaded from a storage device (the hard disk, usually) into RAM, and they remain there as long as your computer is running.
· RAM contents changes as programs are executed.
· RAM chips consist of millions of switches that are sensitive to changes in electric current.
· RAM chips are typically packaged on small circuit boards called memory modules, which are inserted into special slots on the motherboard.
· On booting, operating system files are loaded from a storage device (the hard disk, usually) into RAM, and they remain there as long as your computer is running.
· RAM contents changes as programs are executed.
· The amount of RAM needed depends on the types of applications you intend to run on the computer. S/w indicates the minimum amount of RAM required to run.
Two basic types of RAM are Dynamic RAM (DRAM), and Static RAM (SRAM).
Most computers today use DRAM, which is also of two types:
· SDRAM Synchronous Dynamic RAM runs at the same pace as the system clock runs
· DDR SDRAM DDR stands for Double Data Rate - runs at double the pace the system clock runs - available in speeds from 266 MHZ up to 600MHZ
· DDR2 SDRAM runs at four times the pace the system clock runs - available in speeds from 400 MHZ up to 800MHZ

Most desktops and notebooks use one of the three most popular types of synchronous dynamic random access memory (SDRAM) for the main system memory. Single data rate (SDR) SDRAM is the older type of memory, commonly used in computers prior to 2002. Double data rate (DDR) SDRAM hit the mainstream computer market around 2002, and DDR2-based systems hit the market in mid-2004.

DDR SDRAM is a straightforward evolution from SDR SDRAM. The big difference between DDR SDRAM and SDR SDRAM is that DDR reads data on both the rising and falling edges of the clock signal, so the DDR module can transfer data twice as fast as SDR SDRAM.

While DDR has a limited clock rate, the evolutionary changes to DDR architecture enable DDR2 to achieve speeds beyond of DDR, delivering bandwidth of 5.3 GB per second and beyond! Because DDR2 is able to operate with faster bus speeds, your memory doesn't hold back the performance of your processor.

Generally speaking, motherboards are built to support only one type of memory. You cannot mix and match SDRAM, DDR, or DDR2 memory on the same motherboard in any system. They will not function and will not even fit in the same.

Why is RAM so important?

Aside from the processor, the two most important factors affecting a PC's performance are RAM and hard disk capacity.

Hard disks are typically huge, so the primary limiting factor is the amount of installed RAM. Without enough RAM, the operating system must swap out storage space with the hard disk. The OS creates a Paging File (swap file) to supplement RAM (workspace). This is Virtual Memory.

Virtual memory is inherently slow! RAM speed can typically be 120,000 times FASTER than the hard disk so the less you must rely on virtual memory (swapping files between RAM and hard disk), the faster your system will perform.

Microprocessor

· Heart and brain of the PC

· One electrical circuit in control of another

· Successive generation of processors

· 80286,80386,80486 -32 bit interface

· Pentium family P1, P2, P3, P4 64 bit interface

· Dual-core technology is like having two processors - A dual-core processor is a CPU with two separate cores residing on the same chip

Definitions of computers hardware basic Coding Schemes Computer Peripherals

What is a Computer?

· An electronic machine

o that can be programmed to

o accept data (input), and

o process it into

o useful information (output).

· Kept in secondary storage (storage) for safekeeping or later use.

· The processing of input into output is directed by the software, but performed by the hardware.

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