Specifications

Appendix A: Chip Set & I/O Map
AA
Page A-3
Second Interrupt Controller:
R400 emulating 8259 of PC/AT
I/O Addr Functional group Usage
0A0 Interrupt controller 2 Port 0
0A1 Port 1
Second (16-bit) DMA Controller:
R400 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