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Board Description and Memory Maps
1
ISA DMA Channels
There are seven ISA DMA channels in the PIB. Channels 0 through 3
support only 8-bit DMA devices while Channels 5 through 7 support only
16-bit DMA devices. These DMA channels are assigned as follows:
Note Because the Z85230 is an 8-bit device and Channels 5 and 6 are
16-bit DMA Channels, only every other byte (the even bytes)
from memory is valid.
Table 1-20. Two Wire Serial (I
2
C) Bus Addresses
I
2
C Bus Address Function
1010000 Bank A lower DIMM
1010001 Bank A upper DIMM
1010010 Bank B lower DIMM
1010011 Bank B upper DIMM
Table 1-21. PIB DMA Channel Assignments
PIB Priority PIB Label Controller DMA Assignment
Highest Channel 0 DMA1 Serial Port 3 Receiver (Z85230 Port A Rx)
Channel 1 Serial Port 3 Transmitter (Z85230 Port A Tx)
Channel 2 Floppy Drive Controller
Channel 3 Host Parallel Port
Channel 4 DMA2 Not available - Cascaded from DMA1
Channel 5 Serial Port 4 Receiver (Z85230 Port B Rx)
Channel 6 Serial Port 4 Transmitter (Z85230 Port B Tx)
Lowest Channel 7 Peripheral Parallel Port
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