HP 7942 Service Manual page 61

MNEMONIC
WGATE-·L
WMFM+,
WMFM-
WS
Theory of Operation
7942 and 7946
Table 3-1. List of Mnemonics (Continued)
SIGNAL
Write Gate
MFM
Data
Write
Write Select
SOURCE
A2
m
A2
m
Al
III
DESCRIPTION
If the disc drive is deselected, the
microprocessor will re -examine the
fault and reactivate itself if the con-
dition clears.
ST- 506 Interface control signal.
When WGA TE-L is active (low), it
enables write data to be written on
the disc. When inactive (high), it en-
abIes data to be read from the disc.
Output to disc drive assembly Al
III
via cable W 3.
ST-506 Interface data signal. A dif-
ferential MFM signal which defines
the transitions to be written on a
track. The transition of the WMFM+
line going more positive than the
WMFM - line will cause a flux rever-
salon a track (provided that Write
Gate WGATE-L is active). Output to
disc drive assembly A I
III
via cable
W3.
Selects the read or write mode of
operation for the preamplifier/write
driver IC's in the head -disc module.
When WS is high, the write mode is
selected; when WS is low, the read
mode is selected.
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