General Description - Northern Telecom BCS35 Replacement Manual

High Performance DISK Interface
circuit pack

General description

The High Performance (H.P.) Disk Interface circuit pack, in slot 11 of the A
and B chassis, is a smart circuit assembly, with its own Z80 microprocessor,
EPROM, local RAM, and dual–ported RAM. It is a peripheral of the
microprocessor on the main CPU at slot 1.
The H.P. Disk Interface circuit pack is the link to the disk drive and transfers
data to and from the bus used for recording on or reading from the disk. The
stored program on the H.P. Disk Interface circuit pack provides the write and
read commands to the disk drive.
System interface is via the 100–pin edge connector.
See Table 8–1 for the two option jumpers on the circuit pack. Figure 8–1
shows jumper locations and circuit pack layout.
Replacing the H.P. Disk Interface circuit pack
Use the following procedure to replace this circuit pack.
DPP Card Replacement Guide BCS35 and up
69