Computer System





U=Used For







1.An electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program.


2.A computer is a programmable machine that receives input, stores and manipulates data//information, and provides output in a useful format.


3.A programmable device that performs mathematical calculations and logical operations, especially one that can process, store and retrieve large amounts of data very quickly.


A computer contains several major subsystems such as the Central Processing Unit (CPU), memory, peripheral device controllers etc.


Some Important Words




The Accelerated Graphics Port is a high speedconnection to the motherboard for video cards.


Faster than a PCI card and doesn’t use the systemmemory.




The Basic Input/Output System controls thecomputer’s basic operations and is responsible forstarting up the computer and hardware.




Short for Binary digit. It is the smallest unit ofinformation handled by a computer. One bitexpresses a 1 or a 0 in a binary numeral.


Or, it’s a true or false logical condition, and isrepresented physically by an element such as ahigh or low voltage at one point in a circuit or asmall spot on a disk magnetized one way oranother.


A single bit conveys little information a humanwould consider meaningful.


A group of 8 bits, however, makes up a byte,which can be used to represent many types ofinformation, such as a letter of the alphabet, adecimal digit, or other character.



Bus Speed


Measured in MegaHertz (MHz) and determines howfast the memory and CPU run.





The case holds, cools, and protects the computer; thebigger the better.



CD-ROM and CD-ROM Burner (CD-R/CD-RW)


This device reads data, audio, and video files froma CD-ROM disc.


A burner can also save and even re-save data to aCD-ROM.





The Central Processing Unit is the computer’s controlcenter: the “brain”.





It reads the same as a CD-ROM but is a supercompressed format (MPEG) that can store full-lengthmovies.



Floppy Drive


Magnetic storage medium. Sealed in a hard plasticshell, the actual magnetic disk is flexible plasticcoated with a layer of magnetic film.


Typical floppy disks hold 1.4 megabytes of dataand measure 3.5 inches in diameter.


Floppy disk drives connect to the motherboard viaa dedicated cable.


Old floppy disks were 5 1/4 in.



Hard Drive


This stores all of the computer’s information andretains the information when the computer is turnedoff.



Allows the entry of data and executes programs.



Megabytes (MB)


It is used to measure the amount of space on a harddrive or on a memory stick.


Gigabytes (GB) are more frequently used now.





It is a high resolution TV-like tube that displays thecomputer’s output.





This transfers data between all of the computer’s components: the human nervous system.





Allows the entry of data and executes programs theeasy way on screen and works well with graphics andicons.





The “Peripheral Component Interconnect” is a highspeedconnection to adding devices to a computerincluding SCSI cards, video, sound, modems, andother PCI devices.



Power Supply or SMPS


Converts power from a source into power thecomputer can use.


300 – 400 watt supply cases are best. Smallermeans more crashes.


Aids in the cooling of the computer.


Switch Mode Power Supply





It outputs data that is seen on the screen or from afile.





Random Access Memory holds recently accesseddata from the computer for the CPU to have quickaccess to.


It is gone once the computer is shut off.





This device allows the reading of images and text.





The “skuzzy” stands for “Small Computer SystemsInterface”.


This interface is the fastest connection to the harddrive and is usually associated with the harddrive(s).





A connecting device used on Ethernet networks.Each computer on the Local Area Network isconnected to the switch with a dedicated segment.


The switch uses the MAC or ISP address todetermine which segment to forward frames to.


A frame is only forwarded to the destination ratherthan broadcast to all computers.


This increases both the security and the efficiencyof the network.


Contrast with a Hub simply forwards all datathrough the network.





The Universal Serial Bus Port allows for theconnecting of many external devices to the computer.



Video Card


It transfers data from the computer to the monitor. 3-D cards are necessary for games.



Computer Parts                                            



Touch And See                                                                                           

Ex-Printer,Moniter,Mouse etc



Needed To Make Computer Work

Instructions Tell To Cpu,What To Do


Ex-Word Processing,Games,Spreadsheet,s etc


3.CPU (Central Processing Unit)

Control Unit

Arithmetic Unit

Immediate Access Store

Brain Of The Computer

Where All Processing Takes Place


Ex-Silicon Chip,Intel Pentium Processor


Main Memory



RAM (Random Access Memory)


Data Erased When Power Lost

Data Held Only Temporarily

ROM(Read Only Memory)


Programs Related To Operating System Stored In ROM



Binary Code 0 & 1

Binary Digit

8 Bits Make A Byte



ASC-II Code Used To Encode Alphabet

1000 Characters = 1000 Bytes Or 1 Kilobytes

1000 Kilobytes = 1 Megabyte

1000 Megabytes = 1 Gigabyte 




General-Purpose Computers Require


Memory : Enables a computer to store, at least temporarily, data and programs.


Mass Storage Device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.


Input Device : Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.


Output Device : A display screen, printer, or other device that lets you see what the computer has accomplished.


Central Processing Unit (CPU): The heart of the computer, this is the component that actually executes instructions.



Computers Classified By Size And Power


Personal Computer : A small, single-user computer based on amicroprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.


Workstation : A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.


Minicomputer : A multi-user computer capable of supporting from 10 to hundreds of users simultaneously.


Mainframe : A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.


Supercomputer : An extremely fast computer that can perform hundreds of millions of instructions per second.