Welcome to Upgrading & Repairing PC's.This site is for people who want to learn more
about the basics of computers.It covers the full range of PC-compatible
systems from the oldest 8-bit machines to the latest in high-end 64-bit
workstations.
The term PC stands for personal computer,XT stands stands for an eXTended PC
and AT stands for an Advanced Technology PC.The XT systems had an 8-bit 8088
processor and an 8-bit Industry Standard Architecture (ISA) bus for system
expansion.More advanced systems are said to be AT-class,which indicates that
they follw certain standards and follow the basic design first set forth in the
original IBM AT system.AT-class systems must have any processor that is compatible
with Intel 286 or higher processors,including the 386,486,Pentium,Pentium Pro
and Pentium 2 processors,and must have a 16-bit or greater system bus.
