ISA (Industry Standard Architecture) 8-bit expansion slot used in IBM PC and XT clones from 1981, providing an 8-bit data bus and 20-bit address bus for expansion cards at 4.77 MHz.
| Pin | Name | Function | Type |
|---|---|---|---|
| A1 | /IOR | I/O read active low | I/O |
| A2 | /IOW | I/O write active low | I/O |
| A3 | /MEMR | Memory read | I/O |
| A4 | /MEMW | Memory write | I/O |
| A5 | -OCS16 | 16-bit I/O cycle | I/O |
| B1 | GND | Ground | GND |
| B2 | RESET_DRV | System reset | I/O |
| B3 | +5V | 5V power | PWR |
| B8 | IRQ2 | Interrupt request 2 | I/O |
| B14 | DRQ1 | DMA request 1 | I/O |
| B31 | D0 | Data bus bit 0 | I/O |
| B32 | D1 | Data bus bit 1 | I/O |