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MVME5100 Single Board Computer Programmer's Reference Guide

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ISA DMA Channels<br />

PIB<br />

Priority<br />

IPMC7xx ISA Bus Resources<br />

There are seven ISA DMA channels in the PIB. Channels 0 through 3<br />

support only 8-bit DMA devices while Channels 5 through 7 support only<br />

16-bit DMA devices. These DMA channels are assigned as follows:<br />

Table 1-22. PIB DMA Channel Assignments<br />

PIB Label Controller DMA Assignment<br />

Highest Channel 0 DMA1 Serial Port 3 Receiver (Z85230 Port A Rx)<br />

Channel 1 Serial Port 3 Transmitter (Z85230 Port A Tx)<br />

Channel 2 Floppy Drive Controller<br />

Channel 3 Parallel Port<br />

Channel 4 DMA2 Not available - Cascaded from DMA1<br />

Channel 5 Serial Port 4 Receiver (Z85230 Port B Rx)<br />

Channel 6 Serial Port 4 Transmitter (Z85230 Port B Tx)<br />

Lowest Channel 7 Not Used<br />

Note Because the Z85230 is an 8-bit device and Channels 5 and 6<br />

are 16-bit DMA Channels, only every other byte (the even<br />

bytes) from memory is valid.<br />

http://www.motorola.com/computer/literature 1-39<br />

1

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