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ISA

ISA=Industry Standard Architecture

62+36 PIN EDGE CONNECTOR MALE (At the card)
62+36 PIN EDGE CONNECTOR FEMALE (At the computer)

62+36 PIN EDGE CONNECTOR MALE at the card.
62+36 PIN EDGE CONNECTOR FEMALE at the computer.

Pin Name Dir Description
A1 /I/O CH CK <-- I/O channel check; active low=parity error
A2 D7 <-> Data bit 7
A3 D6 <-> Data bit 6
A4 D5 <-> Data bit 5
A5 D4 <-> Data bit 4
A6 D3 <-> Data bit 3
A7 D2 <-> Data bit 2
A8 D1 <-> Data bit 1
A9 D0 <-> Data bit 0
A10 I/O CH RDY <-- I/O Channel ready, pulled low to lengthen memory cycles
A11 AEN --> Address enable; active high when DMA controls bus
A12 A19 --> Address bit 19
A13 A18 --> Address bit 18
A14 A17 --> Address bit 17
A15 A16 --> Address bit 16
A16 A15 --> Address bit 15
A17 A14 --> Address bit 14
A18 A13 --> Address bit 13
A19 A12 --> Address bit 12
A20 A11 --> Address bit 11
A21 A10 --> Address bit 10
A22 A9 --> Address bit 9
A23 A8 --> Address bit 8
A24 A7 --> Address bit 7
A25 A6 --> Address bit 6
A26 A5 --> Address bit 5
A27 A4 --> Address bit 4
A28 A3 --> Address bit 3
A29 A2 --> Address bit 2
A30 A1 --> Address bit 1
A31 A0 --> Address bit 0
B1 GND   Ground
B2 RESET --> Active high to reset or initialize system logic
B3 +5V   +5 VDC
B4 IRQ2 <-- Interrupt Request 2
B5 -5VDC   -5 VDC
B6 DRQ2 <-- DMA Request 2
B7 -12VDC   -12 VDC
B8 /NOWS <-- No WaitState
B9 +12VDC   +12 VDC
B10 GND   Ground
B11 /SMEMW --> System Memory Write
B12 /SMEMR --> System Memory Read
B13 /IOW --> I/O Write
B14 /IOR --> I/O Read
B15 /DACK3 --> DMA Acknowledge 3
B16 DRQ3 <-- DMA Request 3
B17 /DACK1 --> DMA Acknowledge 1
B18 DRQ1 <-- DMA Request 1
B19 /REFRESH <-> Refresh
B20 CLOCK --> System Clock (67 ns, 8-8.33 MHz, 50% duty cycle)
B21 IRQ7 <-- Interrupt Request 7
B22 IRQ6 <-- Interrupt Request 6
B23 IRQ5 <-- Interrupt Request 5
B24 IRQ4 <-- Interrupt Request 4
B25 IRQ3 <-- Interrupt Request 3
B26 /DACK2 --> DMA Acknowledge 2
B27 T/C --> Terminal count; pulses high when DMA term. count reached
B28 ALE --> Address Latch Enable
B29 +5V   +5 VDC
B30 OSC --> High-speed Clock (70 ns, 14.31818 MHz, 50% duty cycle)
B31 GND   Ground
       
C1 SBHE <-> System bus high enable (data available on SD8-15)
C2 LA23 <-> Address bit 23
C3 LA22 <-> Address bit 22
C4 LA21 <-> Address bit 21
C5 LA20 <-> Address bit 20
C6 LA18 <-> Address bit 19
C7 LA17 <-> Address bit 18
C8 LA16 <-> Address bit 17
C9 /MEMR <-> Memory Read (Active on all memory read cycles)
C10 /MEMW <-> Memory Write (Active on all memory write cycles)
C11 SD08 <-> Data bit 8
C12 SD09 <-> Data bit 9
C13 SD10 <-> Data bit 10
C14 SD11 <-> Data bit 11
C15 SD12 <-> Data bit 12
C16 SD13 <-> Data bit 13
C17 SD14 <-> Data bit 14
C18 SD15 <-> Data bit 15
D1 /MEMCS16 <-- Memory 16-bit chip select (1 wait, 16-bit memory cycle)
D2 /IOCS16 <-- I/O 16-bit chip select (1 wait, 16-bit I/O cycle)
D3 IRQ10 <-- Interrupt Request 10
D4 IRQ11 <-- Interrupt Request 11
D5 IRQ12 <-- Interrupt Request 12
D6 IRQ15 <-- Interrupt Request 15
D7 IRQ14 <-- Interrupt Request 14
D8 /DACK0 --> DMA Acknowledge 0
D9 DRQ0 <-- DMA Request 0
D10 /DACK5 --> DMA Acknowledge 5
D11 DRQ5 <-- DMA Request 5
D12 /DACK6 --> DMA Acknowledge 6
D13 DRQ6 <-- DMA Request 6
D14 /DACK7 --> DMA Acknowledge 7
D15 DRQ7 <-- DMA Request 7
D16 +5 V    
D17 /MASTER <-- Used with DRQ to gain control of system
D18 GND   Ground
Note: Direction is Motherboard relative ISA-Cards.
Note: B8 was /CARD SLCDTD on the XT. Card selected, activated by cards in XT's slot J8
Contributor: Joakim Ögren , Rob Gill
Sources: IBM PC/AT Technical Reference, pages 1-25 through 1-37
Sources:  comp.sys.ibm.pc.hardware.* FAQ Part 4, maintained by Ralph Valentino
Please send any comments to Joakim Ögren.