The PC case or cabinet of a computer is a tall and thin sheet metal enclosure that houses various computer equipments such as Motherboard, Power supply, Hard disk, Floppy disk drive, CD drive, DVD drive etc.

• Cabinets are offered in two styles - desktop and tower. These days tower type cabinets are more popular. It stands upright and its height is much more than its width.

• Tower cabinets are offered in two main sizes – one that can fit ATX (12” wide) motherboards and one that can fit ATX mini (8.5” wide) motherboards.

• Cabinets are generally available in two main colors – one is white and other is black. The most commonly used cabinets are from INTEX, FRONTECH, HCL etc.

MOTHERBOARD

A motherboard is the central or primary circuit board making up a complex electronic system, such as a modern computer. It is also known as a mainboard, baseboard, systemboard, or on Apple Computers, a logicboard.

The basic purpose of the motherboard is to provide the electrical and logical connections by which the other components of the system communicate.

The motherboard of a computer consists of a large PCB. It holds microprocessor, main memory, and other essential components on it. Other components such as external storage, controllers for video display and sound and other computer peripherals are attached to the motherboard via edge connectors (sockets, slots and headers) and cables.

The main components attached to the motherboard are :

• MICROPROCESSOR – It is also known as C.P.U. or Central Processing Unit. It is the heart of every computer. All the processing and controlling is done here. The microprocessors used these days are P4, Pentium D, AMD etc.

• BIOS – Basic Input Output System is a non-volatile memory that contains configuration information about the PC. It contains all the codes required for the CPU to communicate with the keyboard, mouse, video display, disk drives etc.

• RTC – RTC or Real Time Clock chip keeps date, time in a 24 hours format.

• CHIP SETS – These are large chips that integrate many functions. They save space and cost. It forms an interface between the CPU’s front-side bus, main memory and other peripheral buses.

• MEMORY SLOTS – These are the slots into which computer’s main memory is installed. This memory is generally chips which are known as RAM. These days the generally used RAM is 512MB, 1GB etc.

• POWER CONNECTORS – These are the connectors and circuits which receive electrical power from the computer power supply and distribute it to the all parts of computer.

• EXPANSION CARDS – The most commonly used expansion card connectors are :

• ISA – Industry Standard Architecture connectors were firstly used in IBM PC’s in 1981. They are black in color. They are not used commonly these days.

• PCI – Peripheral Component Interconnect is a newer version connector. It is white in color. It has replaced ISA connectors in most of the PC’s. It was created in mid-1993.

• AGP – Accelerated Graphics Port is a connector that is specially designed to work with modern video cards. It is brown in color.



POWER SUPPLY

• A computer power supply unit (PSU) or Modulator Power supply Unit (MPS) is the component that supplies power to a computer.

• A power supply is typically designed to convert 220-440V AC power from the mains to usable low voltage DC power for the internal components of the computer.

• It supplies power through a 20 conductor cable to the motherboard.

• It also supplies power to the different drives (HDD, FDD, CD, DVD etc.)

• Modern power supplies are designed to turn on and off using a signal from the motherboard and provide support for modern functions such as the standby mode available in many computers.


HARD DISK DRIVE

• A hard disk drive (HDD), commonly referred as a hard drive or hard disk is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces.

• The first hard disk was invented by Reynold Johnson on September 13, 1956.

• Data is stored on platters which are made from a non magnetic material, usually glass or aluminium and are coated with a thin layer of magnetic material.

• Hard-disk are generally of two types-ATA and SATA. The SATA hard-disks are used these days because they are faster.

• The most commonly used hard-disks according to their storage capacity are 40GB, 80GB, 160GB etc.

• The most commonly used hard-disks are of Samsung and Seagate companies.

• An 80GB hard-disk sells for about Rs.1800 in the market and 160GB hard-disk for about Rs.2300.


FLOPPY DISK DRIVE

• A Floppy Disk is a data storage device that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell.

• Floppy disks are read and written by Floppy Disk Drives or FDD.

• The FDD installs in one of the external drive bays at the front of the PC cabinet and is secured by screws. Here external means you can access the FDD from outside.

• The Floppy Disk Drive was invented by IBM in 1969.

• The floppy disks are available in two formats- 3.5” and 5.25” forms.

• A floppy disk can store 1.44MB of data.

• A floppy can be bought for 10-15 rupees.

• Due to increase in usage of CD’s and DVD’s floppy disks are not used commonly these days.