PC ISA Card Pinout and Board Size

ISA PC Card Size

ISA PC Card Description

The PCXT bus uses the J1 A/B rows, and a PCAT bus [ISA Bus] uses the J1 [A/B rows] and J2 [C/D rows] connectors. The fingers are copper strips on the PWB spaced on 0.1 inch centers. The PCAT bus was an up-grade to the original PCXT bus. The Pin-Out for both bus types are shown in the table above. The connector positions and relationship to the board are shown in the two figures at the top of the page. Both figures show a PCAT card, but the first figure also shows an attached PCI bus. Example dimensions for the card sizes are provided. Some of the signal names provided in the pin-out table are not correct terms. For example the Address lines called out above would be called SA# [SA19 - SA0], and the Data lines would be called SD# [SD15 - SA0]. The IBM compatible AT card [ISA] used the standard (edge) connector provided by the XT bus and added an additional edge connector behind that with the same pin-spacing @ 0.1 inch center-to-center. The additional connector has only 36 fingers (18 per side), while the XT connector had 62 fingers (32 per side). The Personal Computer Motherboard could then accept either an 8 or 16 bit card in an 8 bit slot (XT), or (if the connector was provided) a 16 bit card in an AT slot. A maximum number of 8 Expansion slots were provided on IBM compatible Motherboards. The ISA clock ran at around 10MHz. The ISA bus is obsolete and should not be used with new computer systems.

ISA PC Pinout and Signal Names

**PC [ISA] XT/AT Connector Pin Out**
Pin	J1		J2
#	A Row	B Row	C Row	D Row
1	Channel Check	Ground	System Enable	Memory 16 bit select
2	Data 7	Reset	Unlatched Address 23	I/O 16bit Chip Select
3	Data 6	+5v	Unlatched Address 22	IRQ10
4	Data 5	IRQ9	Unlatched Address 21	IRQ11
5	Data 4	-5v	Unlatched Address 20	IRQ12
6	Data 3	DMA Request 2	Unlatched Address 19	IRQ15
7	Data 2	-12v	Unlatched Address 18	IRQ14
8	Data 1	Zero Wait State	Unlatched Address 17	DMA ACK0
9	Data 0	+12v	Memory Read	DMA Request 0
10	I/O Channel Ready	Ground	Memory Write	DMA ACK5
11	Address Enable	Real Memory Write	Data 8	DMA Request 5
12	Address 19	Real Memory Read	Data 9	DMA ACK6
13	Address 18	I/O Write	Data 10	DMA Request 6
14	Address 17	I/O Read	Data 11	DMA ACK7
15	Address 16	DMA ACK3	Data 12	DMA request 7
16	Address 15	DMA Request 3	Data 13	+5v
17	Address 14	DMA ACK1	Data 14	Master
18	Address 13	DMA Request 1	Data 15	Ground
19	Address 12	Refresh	N/A	N/A
20	Address 11	CLK	N/A	N/A
21	Address 10	IRQ7	N/A	N/A
22	Address 9	IRQ6	N/A	N/A
23	Address 8	IRQ5	N/A	N/A
24	Address 7	IRQ4	N/A	N/A
25	Address 6	IRQ3	N/A	N/A
26	Address 5	DMA ACK2	N/A	N/A
27	Address 4	Terminal Count	N/A	N/A
28	Address 3	Address Latch En	N/A	N/A
29	Address 2	+5v	N/A	N/A
30	Address 1	Oscillator	N/A	N/A
31	Address 0	Ground	N/A	N/A

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Electronic Engineering Design Key words: PC, Personal Computer, PCAT, PCXT, ISA, PCI, Industry Standard Architecture Bus, Pinout, P2/J2 Pinouts, P1/J1 Pin-out, J1 (A/B), J2 (C/D), Pin Outs, Connector, Signal Names, Pin descriptions, Card size, PWB Board Mechanical Dimensions, Mechanics Description, Electrical Interface, IC, Parallel Bus, Physical Interface, Obsolete, Out-Dated, Legacy.


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