user manual

Programming Considerations

http://www.motorola.com/computer/literature 2-13

DMA Channels

The PIB supports seven DMA channels. Channels 0 through 3 support

8-bit DMA devices. Channels 5 through 7 are dedicated to 16-bit DMA

devices. The channels are allocated as follows:

Sources of Reset

The MVME2603/2604 SBC has eight potential sources of reset:

1. Power-on reset

RESET switch (resets the VMEbus when the MVME2603/2604 is

system controller)

3. Watchdog timer Reset function controlled by the SGS-Thomson

MK48T559 timekeeper device (resets the VMEbus when the

MVME2603/2604 is system controller)

Table 2-3. IBC DMA Channel Assignments

IBC

Priority

IBC

Label

Controller DMA Assignment

1 Channel 0 DMA1 Serial Port 3 Receiver (Z85230 Port A Rx)

2 Channel 1 Serial Port 3 Transmitter (Z85230 Port A

Tx)

3 Channel 2 Floppy Drive Controller

4 Channel 3 Parallel Port

5 Channel 4 DMA2 Not available — Cascaded from DMA1

6 Channel 5 Serial Port 4 Receiver (Z85230 Port B Rx)

7 Channel 6 Serial Port 4 Transmitter (Z85230 Port B

Tx)

8 Channel 7 Not Used