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                專注電子技術學習與研究
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                isa總線標準定義

                作者:佚名   來源:不詳   點擊數:  更新時間:2008年01月08日   【字體:

                isa總線標準
                ISA 是 Industry Standard Architecture 的縮寫 ISA插槽是基于ISA總線(Industrial Standard Architecture,工業標準結構總線)的擴展插槽,其顏色一般為黑色,比PCI接口插槽要長些,位于主板的最下端。其工作頻率為8MHz左右,為16位插槽,最大傳輸率16MB/sec,可插接顯卡,聲卡,網卡已及所謂的多功能接口卡等擴展插卡。其缺點是CPU資源占用太高,數據傳輸帶寬太小,是已經被淘汰的插槽接口。

                 ISA 是8/16bit 的系統總線,最大傳輸速率僅為8MB/s ,但允許多個CPU 共享系統資源。由于兼容性好,它在上個世紀80年代是最廣泛采用的系統總線,不過它的弱點也是顯而易見的,比如傳輸速率過低、CPU占用率高、占用硬件中斷資源等。后來在PC‘98 規范中,就開始放棄了ISA 總線,而Intel 從i810 芯片組開始,也不再提供對ISA 接口的支持。

                    ISA總線擴展插槽由兩部分組成,一部分有62引腳,其信號分布及名稱與PC/XT總線的擴展槽基本相同,僅有很小的差異。另一部分是AT機的添加部分,由36引腳組成。這36引腳分成兩列,分別稱為C列和D列。  

                isa接口卡的外觀

                 

                isa插槽的外觀

                 

                ISA接口引腳定義


                引腳

                定義

                方向

                說明

                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

                關閉窗口
                好深好猛在公车上

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