isa接口定义
isa接口定义

ISA 是 Industry Standard Architecture 的缩写 ISA插槽是基于ISA总线（Industrial Standard Architecture，工业标准结构总线）的扩展插槽，其颜色一般为黑色，比PCI接口插槽要长些，位于主板的最下端。其工作频率为8MHz左右，为16位插槽，最大传输率16MB/sec，可插接显卡，声卡，网卡已及所谓的多功能接口卡等扩展插卡。其缺点是CPU资源占用太高，数据传输带宽太小，是已经被淘汰的插槽接口。ISA 是8/16bit 的系统总线，最大传输速率仅为8MB/s ，但允许多个CPU 共享系统资源。由于兼容性好，它在上个世纪80年代是最广泛采用的系统总线，不过它的弱点也是显而易见的，比如传输速率过低、CPU占用率高、占用硬件中断资源等。后来在PC‘98 规范中，就开始放弃了ISA 总线，而Intel 从i810 芯片组开始，也不再提供对ISA 接口的支持。



ISA总线扩展插槽由两部分组成，一部分有62引脚，其信号分布及名称与PC/XT总线的扩展槽基本相同，仅有很小的差异。另一部分是AT机的添加部分，由36引脚组成。这36引脚分成两列，分别称为C列和D列。

16位卡(62+36=98pin)

98 pin (62+36)ISA EDGE 公头

98 pin (62+36)ISA EDGE 母头

　

8位卡(62pin)

(At the card)

(At the computer)

　

ISA=Industry Standard Architecture

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