Table of Contents
Advertisement
MNEMONIC
RED-L
REN-L
RMFM+,
RMFM-
SEL-L
SKCMP-L
SRQ-L
STEP-L
TRKO-L
Theory of Operation
7942 and 7946
Table 3-1. List of Mnemonics (Continued)
SIGNAL
Red
Remote Enable
MFM Read Data
Select
Seek Complete
Service Request
Step
Track
0
SOURCE
A2
III
A5
m
Al
III
A5
m
Al
III
A5
m
A2
III
Al
III
DESCRIPTION
Dri ve for red LED in f ron t panel
FAUL T ION LINE indicator. Output
to the front panel via cable W 4.
HP-IB control line used in conjunc-
tion with other messages to select be-
tween two alternate sources of device
programming data.
ST - 506 In terf ace data signal. A dif-
ferential signal which defines the
MFM transitions recovered by read-
ing a prerecorded track with a selec-
ted head.
The transition of the
RMFM+ line going more positive
than the RMFM - line represents a
flux reversal on the track. Output to
DDC peA - A 2
III
via cable W 4.
DC-IB signal used to select which
DDC will respond to a given con-
trol/status bus operation. When low,
SEL-L selects DDC 0 (disc drive.)
ST- 506
Interface
control
signal.
SKCMP-L
indicates
that
the
read/write heads have settled on the
final track at the end of a seek opera-
tion. Reading or writing should not
be attempted when SKCMP-L is in-
active
(high).
Output
to
DDC
PCA - A 2
III
via cable W 3.
HP - IB
general
managemen t
line.
SRQ-L is used by a device to indicate
the need for service and to request an
interrupt of the current activity.
ST- 506
Interface
control
signal.
STEP-L causes the read/write heads
to move in the direction of motion
defined by Direction signal DIR -
L.
One Step pulse
=
one step
=
one track.
Output to disc drive assembly A I
III
via cable W3.
Indicates when the read/write heads
are positioned at cylinder 0 (the out-
ermost data track). Output to DDC
PCA - A 2
III
via cable W 3.
3-27
Advertisement
Table of Contents
