Computer System Components

We describe the computer system components that make it tick and what counts in those components

A computer is like a brain which can think, calculate, retrieve and organize information for its human master. This brain is supplied with parts that provide allow for input to it and allow it produce output for presentation to the one using it.

Computer Brain

Central Processing Unit

The thinking part of the brain of the computer is the CPU or Central Processing Unit. This component provides all the control and manages calculations and manipulation of data.

Computer manufacturers are always trying to squeeze more speed and multiprocessing capability (doing multiple things at the same time) out of it. This has led to the dual core or multiple core CPU which is popular today. A core is basically a computer so that a dual core computer is really 2 computers in one.

Computer speed is usually measured in GHz which means Gigahertz which in turn mean billions of cycles per second. The basic idea is that the higher the number of cycles, the faster the computer is. Today the computer manufacturers are depending on the combined power of multiple cores to provide the power instead of the number of GHz.


The CPU has no memory. It is like a genius with Alzheimer's. In order for the CPU to access and manipulate data, RAM or random access memory is needed to hold the information that the CPU is working on. The amount of memory that a computer has is probably the most important factor affecting the computer's speed. This is discussed in detail in my article What everyone needs to know in order to do an effective computer speed up.

Modern computer memory sizes are measured in Gigabytes or billions of bytes. Modern PC operating systems need at least 1 gig to perform smoothly.

The buzzwords that are usually associated with memory are;

  • dual channel - 2 streams of data can be moving between the memory and the computer at the same time
  • ddr, ddr2, ddr3 - double data rate versions 1, 2, 3 etc. which are methods of squeezing more speed out of the memory at each step
  • sdram - synchronous dynamic random access memory which is a type of solid state computer memory than has an ordered method of transferring the information that makes it work faster
  • xxx MHz - speed of the memory in MegaHertz. The higher the better.

The bottom line of all these technologies is that they speed up the memory in one way or another.

Memory is supplied in the form of DIMMS dual in-line memory modules. These are elongated chips that supply blocks of memory in multiples of 256 megabytes.

DIMM image
DIMM graphic courtesy of
What's important is the number of DIMM slots that your computer's motherboard has. It generally has 2 or 4. Therefore, assuming a 1 gigabyte DIMM, 2 slots would supply 2 gigs and 4 slots would supply 4 gigs.

Disk drive

The the RAM memory is like the current thoughts or short term memory of a person, the disk drive is the long term memory. It holds a vast amount of data, programs and control software to support computer system and user activity. Current computer storage technology has advanced to the stage that a 100 Gigabyte drive is quite inexpensive. Getting anything less would needlessly limit your ability to store and save information.

Disk memory is much slower than RAM memory but it is much cheaper so that it is used to backup and supplement memory operations.

Operating System

The operating system is the software that contains the logic to control all the computer hardware, software and systems. It provides the capability to interact with the computer and provides access to and control of all the programs. It also defines and maintains a scheme whereby data can by filed on the computer and retrieved when necessary. The most popular operating systems on the PC are Windows XP and Vista with Linux and other variants controlling a mintority of computers. The MAC currently uses OS x which is a variant of the Unix operating system.

Speed of Thought

The impact of the various components of the computer brain and their impact on speed is discussed in What everyone needs to know in order to do an effective computer speed up.

Input and Output


The keyboard is the most direct form of human input to the computer. It can be used to generate data and documents, provide information for commands or to initiate operations on the computer.

The standard keyboard has the typical typewriter QWERTY layout of the letters. There are variations with different arrangements.

Things to consider in a keyboard are wireless or wired, letter layout, additional features such as special keys, numeric keypad and mousepad.


The mouse is a device which allows for easy navigation and manipulation of the computer screen in a graphical way. The forward and backward motions of the mouse are translated into up and down motions on the screen or active window. Right or left motions are translated into right and left motion on the display.

The mouse also has buttons which can be used to select items and initiate programs represente by icons (little pictures that represent programs or functions) or to drop down a context sensitive menu.

Choices of mice included wired or wireless, optical or rubber ball based (optical is MUCH better so the rubber ball should be avoided), 1 button up to 3 button mice, different shapes to better fit one's hands and righty and lefty versions.

Media reader

Modern digital devices such as digital cameras, PDAs, handheld and Mobile computers, telephones, and music players use different types of memory cards to support their operations. Often it is desirable to transfer images, music or data to and from these devices to the computer.

A media reader provides this capability.

The media readers are usually described as 10 to 1, 13 to 1 or 15 to 1 etc. to indicate the number of different types of memory cards supported.


A monitor is a television like electronic device that displays images on its screen that correspond to the computer activity currently occurring.

Issues to consider in a monitor are screen size generally ranging from 15 inches to 27 inches measured diagonally, CRT (almost obsolete) or flat screen, resolution, inputs (this determines what you can connect to it and whether it can serve as your TV screen), analog or digital and widescreen (wider for the same screen height) or not.

Video card

The graphics/video card of a computer converts the electronic signals that the computer generates or transfers to it from external input into visual images. The level of clarity, definition and detail of the images depends on the power of the video card being used.

This item is discussed in detail in my article Video Cards Simplified.


Sound is supported on the PC by electronics that convert digital data into analog sound. It may be built into the motherboard of the computer or it may be provided by an expansion card that is inserted into a slot on the motherboard. Integrated sound is fine for most uses but if you want a rich surround sound type of sound or rich gaming sounds expansion cards can provide this capability.


Computer speakers project the sound generated by the computer to the listener. They range from basic to surround sound and subwoofer units that enhance the bass of the generated sound. One space saving form of speaker is a unit that connects to the bottom of the monitor.

DVD and CD

DVD and CD readers and burners allow for getting input from DVDs and CDS and for creating them. Most software is provided on CDs or DVDs.

Burning software allows users to create backups, transfer files and generate audio or video discs that can be played back on standard players.

This item is discussed in detail in Deciphering DVD and CD.


Modems (modulator-demodulator) is a device that converts the ones and zeroes of a computer into a signal that can be transmitted and vice versa. Phone based modems allow users to use their phone lines to communicate with networks, notably the internet and also allows faxes to be received and sent on the computer. Cable or DSL modems convert internet signals to computer data and vice versa to allow for internet and general network communication.


A network is generally an interconnection of a group of computers. The Internet is nothing more than a huge interconnection of computers.

Obviously, networks allow for transfers back and forth of all sorts of information and media between the computers. This item will be discussed in detail in a different section of this site.


Computer printers generate hard copy output. The output can be documents or graphics.

Some of the main choices in printers are type of printer such as laser or inkjet, black and white or color, output speed and the cost of supplies such as toners or ink cartridges.

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