Specifications

Appendix A: Chipset and I/O Map

08B Channel 5 page register

08F Refresh page register

Table A-8. Port A

I/O Addr Functional group Usage

092 Port A Fast A20 and reset control

Table A-9. EXM Configuration

I/O Addr Functional group Usage

096 EXM Config EXM slot register (part of the

subplane)

Table A-10. Second Interrupt Controller: RadiSys R400EX emulating 8259 of PC⁄AT

I/O Addr Functional group Usage

0A0 Interrupt controller 2 Port 0

0A1 Port 1

Table A-11. Second (16-bit) DMA Controller: RadiSys R400EX emulating 8237 of PC⁄AT

I/O Addr Functional group Usage

0C0 DMA Channel 4 address

0C2 Channel 4 count

0C4 Channel 5 address

0C6 Channel 5 count

0C8 Channel 6 address

0CA Channel 6 count

0CC Channel 7 address

0CE Channel 7 count

0D0 Command/status

0D2 DMA request

0D4 Command register (R)

Single-bit DMA req mask(W)

0D6 Mode

0D8 Set byte pointer (R)

Clear byte pointer (W)

0DA Temporary register (R)

Master clear (W)

0DC Clear mode reg counter (R)

Clear all DMA req mask (W)

0DE All DMA request mask

0EC R400EX index register

0ED R400EX data register

Table A-7. DMA Page Registers: RadiSys R400EX emulating 74LS612 of PC/AT

I/O Addr Functional group Usage