PC
August 11 1981 - IBM Corporation introduced its first PC. This Project was completed by a team of engineers named as Group 13. It had the following features.
- it uses 8088 microprocessor
- a 256 KB of dynamic RAM
- it has one or two 360KB floppy disk drives
- 81 keys keyboard used
- it has one serial (male pins) and one parallel (Female pins) Port
PC-XT
March 8 1983 - IBM Corporation introduced PC-XT . It has many features that were not available in PC, so it is called PC-XT or extended. The features were
- it uses 8088 Microprocessor
- it has a built-in 10MB hard disk
- it has eight I/O expansion slots
- 84/101 keys keyboard used.
- it can support 256KB or 640KB RAM
- it has one serial port and one parallel port
- it has one or two 360KB or 1.2KB FDD
PC-AT
August 14 1984 IBM Corporation introduced PC-AT286 with 80286 micro processor. But later it introduces PC-AT 386 and 486 with more features.
PC-AT286
- it uses 80286 microprocessor
- it has ROM based diagnostics (POST)
- it supports upto 4mb of RAM
- it has one or two 360 KB or 1.2 MB FDD
- it supports upto 80 MB of hard disk
- it has enhanced 101 keyboard
- it has eight I/O expansion slots
PC-AT 386
- it uses 80386 microprocessor
- it supports upto 64MB of RAM
- it supports 1.2MB and 1.44MB FDD
- it supports upto 350MB Harddisk
- it has 64 KB external on board cache
- it has I/O slots and ISA Slots
PC - AT 486
- it uses 80486 microprocessor
- it supports 1MB to 128MB RAM
- it supports CD Drive and 4 IDE Devices
- it has upto 512 KB External Cache
- it supports green PC features, plug and play features
- it has 104 keys windows keyboard
Pentium
In 1983 Intel Corporation introduced a 80586 microprocessor called Pentium. Personal Computers with this processor are called Pentium. The Important features are
- its operating speed is 60 to 200 MHz
- it has 32 bit data bus internally and 64 bit data bus externally
- it uses dual pipelining technique. This increases the speed of execution.
- it supports four harddisk drives of capacity 584MB to 8.4GB
- it supports upto 386MB RAM
- it has two 8KB Primary Cache and 256 to 1MB of external cache (Secondary)
Later, the following versions of pentium systems with a lot of new features. They are
- PC with Pentium Pro Processor
- PC with pentium mmx processor
- PC with pentium II Processor
- PC with pentium III Processor
- PC with pentium IV Processor