A. Jumper Configurations
31
JUMPER DESCRIPTIONS
The following topics list the jumpers in numerical order and provide a detailed
description of each jumper. A dagger (
†
) indicates the default jumper configuration.
W1-2 (DMA Mode Selection)
The ZT 8954 can be used in four DMA modes. The primary mode (Mode 2 DMA) uses
the BUSRQ*/BUSAK* signals on the backplane for DMA request/acknowledge and uses
the backplane control signals for the data transfer. The other modes allow configuration
for slot-specific DMA (Mode 1), frontplane DMA (Mode 3), or a combination of
frontplane and backplane signals for use in STD-80 backplanes (Mode 0).
The control signals are DMAIOR*, DMAIOW*, and T-C for the backplane and DMAW*,
DMAR*, and TC* for the frontplane. Note that frontplane control is a factory option
because the frontplane connector is not nominally loaded. Refer to the
J1 (DMA PORT)
topic in Appendix B, "Specifications."
W2
W1
Mode
Request/Ack.
Control Signals
Out
Out
0
BUSRQ*/BUSAK*
Frontplane
Out
In
1
DRQx*/DAKx*
Backplane
†
In
†
Out
2
BUSRQ*/BUSAK*
Backplane
In
In
3
Frontplane
Frontplane
†
Factory default configuration
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