Acorn Computers Limited Winchester disk 110, Руководство по обслуживанию

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5. Circuit description
The only part of the Winchester Disc unit which is serviceable by Acorn
dealers is the Host Adapter PCB (see appendix for circuit diagram) and its
connectors and cables etc. This is an interface between the asynchronous SCSI
interface to the disc controller board, and the synchronous 1MHz expansion bus
interface on the host microcomputer used by the Winchester Disc filing
system. The following circuit description will provide enough information
about the disc controller board and the 1MHz expansion bus to allow a full
understanding of the operation of the Host Adapter board. For the full
specification of the SCSI interface see the relevant literature.
5.1 The disc controller board
The disc controller used in the Winchester Disc unit is a device which will
send or accept parallel (byte) data to or from the host microcomputer (via
1MHz bus and Host Adapter), and will read or write this data serially to or
from the hard disc. It contains a 256 byte cache memory (hereafter referred to
as the "sector memory" because 1 disc sector = 256 bytes). A connection
diagram for the disc controller board is given in figure 3 below.
Figure 3 Disc controller board connection diagram
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