XT bus architecture

The XT bus architecture is an 8 -bit bus architecture, which found the Intel 8086 and the Intel 8088 in the IBM PC and IBM PC XTs in the early to mid 1980s using. The slot concept was copied substantially from the Apple II.

The XT architecture provides a direct predecessor of dar. in IBM PC -AT machines until the mid- 1990s used 16- bit ISA architecture The AT bus also called ISA bus is to the XT bus backward compatible; most XT -bus expansion cards also work in ISA bus computers, where they occupy only the first of the two sections of the ISA slot.

XT bus has four DMA channels, three of which are led out of the expansion slot. Of these three, two are normally occupied by machine functions:


  • Peripheral bus (internal)