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Functional Description
7936 and 7937
MNEMONIC
SOMP-H
SOX,
SOY
SOO
thru
S07
SEF-L
5-62
SIGNAL
Sampled
Dump
Servo Data
Servo Data,
bits 0 thru 7
Start ECC
Field
Table 5-1. List of Mnemonics (15 of 23)
SOURCE
IJA1
1DJJ
A3
I
A6
A1
IiJII
A2
DESCRIPTION
SAMPLED
SERVO
TIMING
output
to
POSITION
DEMODULATOR.
SOMP-H
controls
the
discharge
of
the
position
demodulator sample-and-hold circuits.
Differential output from the preamplifier
section
of
the
SERVO
READ
PREAMP /WRITE DRIVER IC.
SOX
and
SOY
are
connected
to
the
DEDICATED
SERVO
AMPLIFIER
in
read/write PCA-A2 via HDA cable WS.
Bidirectional parallel S-bit bus in
Servo
Control Bus which carries commands and
status
information
between
the
SERVO
CONTROL
INTERF ACE
in
controller
PCA-A6 and the SERVO CONTROLLER in
PCA-AI. All command and status messages
are two bytes in length, so it requires two
operations to complete a message.
These
transfer operations are fully handshaked by
four lines associated with the bus. These lines
are
Servo
Read
(SRO-L),
Servo
Write
(SWR-L),
Servo Data Available
(SOAV-L),
and
Servo Buffer Full
(SBF-L).
SOO
thru
S07
are connected between con-
troller
PCA-A6 and servo
PCA-AI
via
read/write PCA-A2.
READ/WRITE CONTROLLER Disc Data
Bus handshake line.
SEF-L
goes low during
the 264th data byte of a transfer. During a
read operation, 12 more bytes are sent to the
controller. During a write operation, 14 more
OOS-H
clocks occur. The first two clocks af-
ter the falling edge of
SEF-L
are ignored by
the dat.a path control system, and only the
last 12 bytes are written to the disc. This al-
lows the controller to switch data paths from
the data source driving the bus to the ECC
generator driving the bus.
SEF-L
is connected from the READ/WRITE
CONTROLLER to the DMA/ECC in con-
troller PCA-A6 via connectors A2J 1 and
A6Pl.
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