IBM Series 1 User Manual page 99

Direction loqic for bi-directional address and data
lines is provided on the feature so that its operation is
transparent to the outboard I/O attachments. In the absence
of any activity on the channel. the default direction of the
bidirectional busses is away from the processor. The
repower feature inhibits the outboard signal lines from
affecting the availability of inboard devices when the
outboard attachment or card file is powered down.
The feature has a TTL level coapatible hysteresis
receiver for the outboard pover-oD reset. The receiver has
a maximum current of 100 microamperes, which the outboard
attachment or card file is required to sink at 0.45V (most
positive down level) when powered down or actively
signalling pover-on reset.
The pin assignments for the repower feature are listed
in Figure 2-33. The top card connectors (Tee) are standard
IB~ connectors, and receive standard I/O channel cables.
For reference purposes Tee pins
W02, 102.
Y02, and Z02
correspond to 002, J02, P02, and U02 respectively. Top card
connectors W, X, I and Z correspond to cables
1,
2, 3 and 4
respectively. Therefore, when facing a repower feature that
is plugged into an I/O socket, the W connector is at the top
and would receive cable number 1 (see Figure 2-32).
2-84
GA34-0033
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