XT bus architecture
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Template:Mergewith (The slots in the IBM XT are now called "8 bit ISA slots".)
The XT bus architecture is 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 IBM PC AT 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 disk controller |
See also
- Extended Industry Standard Architecture (EISA)
- Micro Channel Architecture (MCA)
- Peripheral Component Interconnect (PCI)
- This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.