XT bus architecture

hardware, architecture (After the IBM PC XT) An eight-bit

ISA bus architecture used by Intel 8086 and Intel 8088

systems in the IBM PC and IBM PC XT in the 1980s. It

predates the 16-bit ISA architecture used on the Intel 80286

based machines.

The XT bus has four DMA channels, of which three are brought

out to the expansion slots. Of these three, two are

normally allocated to machine functions:

DMA channel Expansion Standard function

0 No dynamic RAM refresh

1 Yes add-on cards

2 Yes floppy disk controller

3 Yes hard disc controller

(1997-09-15)