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Programming the MVME240x

Programming Considerations

Good programming practice dictates that only one MPU at a time have control of the MVME240x control registers. Of particular note are:

Registers that modify the address map

Registers that require two cycles to access

VMEbus interrupt request registers

PCI Arbitration

There are seven potential PCI bus masters on the MVME240x :

Hawk ASIC (MPU/PCI bus bridge controller)

Winbond W83C553 PIB (PCI/ISA bus bridge controller)

DECchip 21143 Ethernet controller

UniverseII ASIC (PCI/VME bus bridge controller)

PMC Slot 1 (PCI mezzanine card)

PMC Slot 2 (PCI mezzanine card)

PCI Expansion Slot

The Winbond W83C553 PIB device supplies the PCI arbitration support for these seven types of devices. The PIB supports flexible arbitration modes of fixed priority, rotating priority, and mixed priority, as appropriate in a given application. Details on PCI arbitration can be found in the MVME2400-Series VME Processor Module Programmer’s Reference Guide.

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Motorola MVME2400 manual Programming Considerations, PCI Arbitration