Personal Computer (PC)
PC is the simplest and cheapest type of personal computer.
It uses Intel 8086/8088 as CPU, 640 KB RAM, 8KB ROM and normally two floppy disk drives.
One of the drives is normally meant for holding bootable floppy diskette and the second one is used for holding the application package as well as for secondary storage.
This type of computer does not contain any hard-disk. It is a single- user system.
Its ROM can be extended from 8KB to 64 KB. It uses MS-DOS operation system. It may also employ 8087 math co-processor.
PC/XT
This type of computer contains hard-disk(s) as well as floppy disk drive i.e. 360 KB/1.2 MB.
Its cost is obviously more than the PC due to additional components. It is also a single-user system.
Its ROM can also be extended up to 64 KB. It also normally uses MS-DOS operation system. It may also employ 8087 math co-processor.
PC/AT
It contains 80286 as CPU, 640 KB RAM (can be expanded to 4 MB), 64 KB ROM (can be expanded to 128 KB), hard-disk drive and floppy-disk drive (360 KB/1.2 MB).
Microprocessor 80286 is more powerful than the microprocessors of PC and PC/XTs.
Up to 4 terminals can be connected to PC/AT to make it multi-user system by using XENIX as an operating system.
Hard-disk capacity may lie in the range 20-80 MB. It uses 80287 math co-processor.
Processing speed of PC, PC/XT and PC/AT lies in the range 1-5 MIPS.
Super AT (or Super micros)
These computers use a 32-bit CPU such as Intel 80386 or 80486.
The processing speed of 80386 and 80496 may range from 3 to 5 MIPS and 12 MIPS at 25 MHz respectively. RAM size of these lie in the range 2-8 MB.
In case of 80386 microprocessor, it can be extended up to 32 MB and in case of 80486 up to 64 MB.
Hard-disk capacity of these lies in the range 200 MB-780 MB. Normally, UNIX is used as a multi-user operating system on these systems.
80386 CPU offers the connectivity up to 8-12 terminals whereas 80486 offers the connectivity up to 16-64 terminals.
Personal computers are available in two models. These are:
1. Desktop PCs
2. Tower PCs
A desktop personal computer is most popular model of personal computer.
The system unit of the desktop personal computer can lie flat on the desk or table.
In desktop personal computer, the monitor is usually placed on the system unit.
Another model of the personal computer is known as tower personal computer.
The system unit of the tower PC is vertically placed on the desk of table.
Usually the system unit of the tower model is placed on the floor to make desk space free and user can place other devices such as printer, scanner etc. on the desktop.
Today computer tables are available which are specially designed for this purpose.
The tower models are mostly used at homes and offices.
Microcomputers are further divided into following categories.
1. Laptop computer
2. Workstation
3. Network computer
4. Handheld computer
Comments