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Functional Description
7936 and 7937
S7t37A77
5-42
SEEK (1)
STORE DPOS (IN PHASE) FOR USE IN LATER
CALCULATION-. IF SSS-O, TCHOLD-l-. QUAD-I
CALCULATE THE FINAL PHYSICAL POSITION
(UNLESS THIS A COMPENSATION SEEK)
.... ...-_--tWAIT lS0u. - . ... _-<
YES
NO
AOU I R-1 ,OUAO-O
CALCULATE HEAD OFFSET QUADRANT, TCHOLO AND
ADJUST OTO
(i f
needed) - . FSEN ,QUAD ,SSS-O
-'AOUIR-l - . CORRECT LSB --. ACCELERATE
IF DTO>611:SEEK T.O.-4Oms,"LAST ACCEL TRK"-
~
_ _ _ .... OTO-281--. IF OTO-21 TO 611 :SEEK T .0.-3Oms,
..:s:::-
"LAST ACCEL TRK"-OTO/2 --- SET A 2ms T
.0.
FOR
FIRST TRACK CROSS I NO ___ 0 I V5-0
'
1
STATUS-26
0IV5,OUAD-l----' START SEEK TIMER--- LOAOI
START TRACK COUNTER
--+
WAI T f'OR
oro-
"LAST
ACEL TRK" --- IF ORIOINAL OTO WAS>
768,
HOLD
VELOCITY AT 65500
TIS
UNTIL DTO-367
~
COAST UNT I L OTO-325 ----- DECELERATE
~WAI
T
FOR OTO-256 ----- 01v5-0 IF OTO < 35
NO
Figure 5-8.
eek Flowchart, (
QSTAT-2
STATUS-2
SEEK TIMEOUT INTERRUPT
DISABLE INTERRUPTS
COAST
FSEN-O
STATuS-l0
., INTERRUPT TIMER IN
EFFECT FOR REMAINDER
OF
SEEK.
ABORT
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