- 2068 Chaitra · 3 marks
Short introduction to ISA bus
Short answer
The ISA bus is the original PC expansion bus, with 8-bit (XT) or 16-bit (AT) data paths, up to 16 MB addressing, and 8 MB/s transfer rate. It uses manual configuration and supports DMA and interrupts, but is obsolete, replaced by PCI.
Give a short introduction of ISA bus.
The ISA (Industry Standard Architecture) bus is the expansion bus of the IBM PC/XT/AT, used to plug adapter cards (serial, parallel, sound, network, disk controllers) into the motherboard.
- XT bus: 8-bit data, 20 address lines (1 MB), 62-pin connector, 4.77 MHz.
- AT (ISA) bus: 16-bit data, 24 address lines (16 MB), added 36-pin connector, 8 MHz (8.33 MHz).
- Signals: address (SA0-SA19, LA17-LA23), data (SD0-SD15), control (MEMR', MEMW', IOR', IOW', BALE, AEN, I/O CH RDY), interrupts (IRQ2-IRQ15), DMA (DRQ, DACK', T/C), power (+5 V, -5 V, +12 V, -12 V).
- Data transfer rate is about 8 MB/s; manual configuration by jumpers; supports DMA and interrupts through the 8237 and 8259.
- Obsolete now; replaced by PCI because of its low speed and lack of plug and play.
✓ Answer checked by Claude Sonnet 5.5
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