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S7U7A7t
SERVO COMMANDS
DISABLE
INTERRUPTS.
RESETS STACK
POINTER, LOADS
AND STORES
UPPER BYTE.
Functional Description
7936 and 7937
.S!I T ARRAY:
SET 400uS T.O.
0:
1 :
2:
3:
4:
5:
s:
7 :
AMP
AGC
LCK
OFT
STE
NO
SPIN-H
SPIN-L
SPIN-B
DECODE THE COMMAND: OPCODE - UPPER BYTE.
SEEK: BIT 15 - 1, BIT 14 - SSSL, BIT 13 - QUAD, BIT 12 - DIR
REST OF BITS - DISTANCE TO GO
RECAL: 04H
SPINUP: 08H
REPORT STATUS: OCH
~
RETURN BIT ARRAY
REPORT SEEK TIME: 10H
~
LAST SEEK TIME IN uS.
REPORT PRESENT TRACK: 14H
PIN TO CRASH STOP: 18H BIT 0 - DIR. BIT 1 - LCK
~FSEN
- 0
QUAD - " DUTY CYCLE - 24uS ON. 12 us OFF (FOREVER)
REPORT SPINDLE SPEED:
20H~'
OF uS/4 SECTORS
ALTERNATE SEEKS: 24H
RANDOM SEEKS: 28H
REPORT HDA TYPE:
30H~
RETURNED IN SIT 0 AND
REPORT LAST VELOCITY: 2CH
BUTTERFLY SEEKS: 34H
HEAD GAIN TEST: 38H. BIT 0 -
DIR~
ACCEL FOR SOOuS.
COAST FOR 40uS. SHUT OFF.
COMPENSATION SEEK:
44H
BIT 7 - DIR, THE REST MUST BE < 3
YES
FIgure 5-1 .
IF FEEDBACK IS
NOT DICTATED BY
THE COMMAND.
BIT 8=OPCODE.
BIT 9-QSTAT AND
STATUS-LOWER BYTE
5-45
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