Servicing Personal Computers, 3rd Edition

Servicing the IBM PC and compatibles 219

of system board RAM (expandable to 640K with 384K fitted in expansion slots). The PC

supported two 360K floppy disk drives, an 80 column x 25 line display, and 16 colours with

an appropriate colour graphics adapter (CGA).

The original PC was quickly followed by the PC-XT. This machine, an improved PC with a

single 360K floppy disk drive and a 10M hard disk, was introduced in 1983. The PC-XT was

followed in 1984 by a much enhanced machine, the PC-AT. This machine uses an 80286

microprocessor (rather than the 8088 used in its predecessors) and offers 256K of system board

RAM.

The standard AT provides 1.2 ...