System Unit

 

SYSTEM UNIT:

The brain behind everything that takes place in pc is contained within the system unit.

(a) Central Processing Unit (CPU):

The Microprocessor or CPU is the computer's most important component. It does all the thinking for the p.c. and runs the programs.

(b) Ram (Random Access Memory) :

When a computer is switched on and is running a program, RAM is used for purpose of holding the program and

its data, but when the p.c. switched off, anything held in ram is lost.

(c) ROM (Read only memory):

In this memory basic start up routines and BIOS (Basic Input Output System programs) are permanently loaded during the manufacturing time. It provides a nonvolatile storage. i.e., the data does not get erased when the power is switched off. It can't be altered and fresh information can't be written into a Rom. It information can be read only

THERE ARE 2 SIDES OF SYSTEM UNITS:
(i)  Front view of system unit
(ii) Back view of the system unit

FRONT VIEW OF SYSTEM UNIT:

(a) Power on/off:
Generally Computers have a main power switch on the front of the system unit.(b) Reset Button :­
This Button can be used to restart computer
(c) Turbo Button :­
Some computers offer a choice of speeds at which they can run.
(d) Key lock :­
This lock prevents the keyboard from working and hence works as a safety lock.(e) Lights :­
System unit may display a verity of colored lights on the front panel.(f) Floppy Disk Drive :­
Computer can have either the 5 1/4" or 3 1/2" floppy drive or both.

Parts of front view:

(1) 5 1/4" floppy drive

(2) 3 1/2" floppy drive

(3) Power on off switch

(4) Push Button for floppy eject

(5) Reset Button

(6) Turbo Button

(7) CPU speed display

(8) Key lock or system lock.

(9) Power indicator light.

(10) Fixed disk drive in use indicator light.

BACK VIEW OF THE SYSTEM UNIT:

(a) Power in and out sockets:
Cables plugged into these sockets carry power from the electrical outlet.(b) Serial Ports :
Serial ports connect computer to a mouse or modem. Most computers are
fitted with two serial ports.(c) Monitor Port :
A cable from monitor plugs into this port and carries the information to
be displayed on the monitor.(d) Parallel Port :
This port is usually used for connecting the computer to printer.(e) Key Board Port :
The cable from keyboard plugs into the key board port.(f) Fan Housing:
The electronic components in pc generate a lot of heat.
To prevent overheating, a fan placed at the back of the unit helps in removing the hot air from system.(g) Compartments for expansion cards:
PCs are easily expandable to provide a modern sound or faster graphics.

INSIDE A SYSTEM UNIT:

The brain behind everything that takes place in pc in contained within the system unit. Inside the unit are components constituting of pc that run programs that handle typed instructions, and determine the results.

(A) Mother Board :­

All the electronic components in a pc are mounted on a piece of fiber glass, called the mother board. A printed circuit board that has slots to connect cards into. they also include a CPU and memory.

(B) Central Processing Unit (CPU) :

The Central Processing Unit is the computer's most important component. It does all the thinking for the pc and runs the programs that you request. Without the CPU, the computer is nothing.

(C) Ram Chips:­

When a computer is switched on and is running a program, Random Access Memory (Ram) is used for purpose holding the program and its data. But when switched off, anything held in Ram is lost.

(D) Floppy Disk Drive :­

Floppy disk drive consists of a slot to accept a floppy a motor that spins the disk, a recording & reading device that moves across the disk in order to read (or) write data.

(E) Hard Disk Drive :­

It is computer's main storage unit, holding large amounts of data and programs. It uses a hard material (typically aluminum).

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