Parts Of Computer

a) Power supply (SMPS-Switch Mode Power Supply):
Generally, at the backside of the CPU box, controls power for all CPU box (Casing)

b) I/O devices:

Is known as input & output devices. (Keyboard, mouse, scanner, digital/ web Camera are input and Monitor, printer, speaker are output devices)

c) Processor - CPU-Central Processing unit:

The CPU is the heart of the computer system. CPU is the most complex computer system component, responsible for directing most of the computer activities based on the instruction provided. Is the most important part of the computer this could be called the brain of a computer.

It has two main parts:

(a) CU-Control Unit

To take stored instructions in sequence, one at a time. To interpret each instruction and prompt its execution by one of the units like input, output, storage or ALU.

(b) ALU-Arithmetic And Logic Unit

To carry out calculations and comparisons based on the instructions.

d) Motherboard

Motherboard is a main board, which is made-up by printed board circuit. In a computer, the necessary electronic components are mounted on a piece of fiberglass board, known as motherboard, which is held inside the CPU box.

e) Memory devices

i) Primary memory

(1) ROM:

ROM (Read Only Memory) chips stores the programs and data at the time of manufacturing a motherboard. ROM is generally called permanent memory. The data ad programs once written are not lost. This is achieved by storing the information into the ROM at the manufacturing stage. The data remain in ROM even when power is switched off. Information can only be read from ROM (of course randomly) it cannot be written into information that never needs to be altered, or that which should be protected form accidental erasure by the user is stored here. For example, the start-up instructions requi4red by the computer are stored in ROM. The program written on the ROM is also called as firmware.

(2) RAM

RAM (Random Access Memory/ Read Write Memory) is used to store programs and data in running computer as a data carrier. The read and write memory of a computer is know as RAM. The users of the computer can write information into RAM, and read information form (RAM) The data and programs entered by the user are stored into RAM. it has the disadvantage it is volatile (i.e the contains of the memory vanish of get erased as the power to the computer is switched off. RAM is available in the form of chip, which constitutes the main or primary memory of the Microcomputers. The storing capacity of RAM is measured in bytes. RAM chips are available in the market with different memory capacity ranging from 4MB, 8MB, 16MB, 32MB, 64MB, 128MB, 256MB, 512MB, 1024MB/(1GB) etc.

ii) Secondary memory

(1) Floppy disk drive

The floppy disk drive of the computer is used to store data or retrieve data from a floppy disk. Floppy: disk are commonly used as secondary and backup storage media in micro computers. They are popularly called diskettes. These diskettes are very thin and flexible and hence, they are called floppy. They are small convenient and inexpensive. They are removable disks .A floppy disk can be inserted into the disk drive when needed. The Physical size are 8”, 5.25”, 3.5”.

(2) Hard disk drive- HDD

The hard disk drive with its hard disk is permanent storing device, which can hold large programs and tremendous amount of information. Hard disks are commonly used as secondary storage media in microcomputer and large computer. Hard disks made of metallic disk coated with metallic side on the both sides. The hard disks are permanently fixed in a drive unit in case of microcomputer. The disk puck is contained in an airtight dust-fee contain. The read write read and access machines are also sealed with the disks. The sped of rotation is about 3600 rpm (re-pollution per minute). The hard disks are available in different sizes. 8 inch, 5.25 inch. It does not make physical contact with the disk surface.This disk always inside the CPU boxes. It storage large volume of information some hard capacities are 630 MB. 1 GB, 2 GB, 8 GB, 10 GB, 20 GB, 40 GB, 40GB, 80GB etc.

Reading and writing:- The hard disk also has a read and writes head that moves ever the desired track to head data from of write data into the disk. A mentioned above the read and write head along with the access arm does not physically touch the disk surface, it floats above the surface of the disk and defaults the data (magnetized data) A hard disk can store much more data than the floppy disk of the same size A 8 inch hard disk could store 20MB where as the same size floppy disk could only 1MB. The hard disks are useful in word-processing and other applications where a large volume of files of data is to be kept.

(3) Compact Disk Drive

The most popular and least expensive type of optical disk is compact disk. CD drive is also an important data storage device known as optical disk drive. The manufactures themselves write data on CD-ROM the CD-ROM is made up of resin. It is coated with a material (eg aluminums), which will change when a high intensity laser beam is focused on it.

Types Of Optical Disk:

1. CD-ROM (Compact Disk-Read Only Memory):- it is an optical ROM which enables prerecorded data to be read. A laser beam is used to write into or read. from CD-ROM. The CD-ROME has very high storing capacity. The read and write head of a CD-ROM drive unit does not touch the disk surface; there is no risk, disk wear of head crash.

2. CD-RW:- (Compact Disk Read Write) While writing high intensity laser beam from as tiny pit along the surface, which represent binary bit 1 absence of bit represents bit 0 while reading CD-ROM, the reflected laser is sensed by photo diode (light sensitive semiconductor dived) The intensity of laser beam changes when the beam encounters pit ie. A pit spreads light so that photo diode little reflected light but the surface with out reflects enough light to the photo diode.

3. Combo Drive: DVD read only and CD Read and Write both.

4. DVD-RW: CD Read, Write & DVD-Read Write both.

Advantages of CD-ROM

CD-ROM has very high storing capacity

They are relatively less expensive.

They have a long life (at least 20 years)

They are comparatively reliable.

CD-ROM can be removed from the drive.