Specifications

8.3.9 Syatem Background Loop Control
If five 90 Jolsec foreground loops have occurred since thal.5t time thiS funetton was entered, then control proceeds
to Loss of Index Monitor; otherwise control goes back
to Spindle Motor Background (paragraph 8.3.6).
8.3.10 Lo .. of Index Monitor
If INDEX has not occurred during the last 115 msec. then control goes to the Control Fault Indicate Function
(paragraph
8.3.3); otherwise control proceeds to Cylinder Address Rezero Monitor.
.
8.3.11 Cylinder Address Rezero Monitor
If the actuator is on cylinder 0 and the exercise jumper (E2) is not installed. then the cylinder address variables are
set to zero; otherwise control proceeds
to the next step.
8.3.12 Seek Ramping Calculate Function
If Ramp Calculate is not enabled by either the Step Input Buffering Fundion (paragraph 8.2.4) or the Drive Ac-
tuator Self-exercise Function (paragraph 8.3.13). the control proceeds to the Drive Actuator Self-exercise Func-
tion. .
If Ramp Calculate is enabled. it accepts the step sum and direction of inputs and produces the necessary seek con-
trol values to effect a buffered seek.
The actuator track zero flag i. monitored and outward seeks from cylinder 0 are
inhibited. unless the delay jumper (E1)
is installed in which CASa such seeks are allowed (this facilitates the adjust-
ment of the crash stop
and track zero flag). .
If the exercise jumper (E2) is installed. the aduator cylinder address variable will be compared with the track zero
flag to detect possible seek errors during self-exercise.
If seek errors are detected. control goes to the Control Fault Indicate Function (paragraph 8.3.3). otherwise control
passes to Drive Actuator Self-exercise Function.
8.3.13 Drive Actuator Self-exercl8e Function
If the exercise jumper (E2) is installed then this routine uses its internal random number generator to create a conti-
nuing series of pseudo-random seek values which insure
full disk coverage dUring exercise.
If the delay jumper (El) is not installed. this function will delay itself for 10.msec; if it is installed. the delay will be
500 msec. If the exercise jumper (E2) is not installed the control proceeds to Actuator Lube Unstick Routine.
8.3.14 Actuator Lube Un.tlck Routine
This routine is enabled by a flag passed hom the Automatic Actuator Reset to Track Zero function. otherwise
.known·as Recal (recalibrate).
It seeks from cylinder 0 to the end cylinder and back twice. It enables the damping
function when
done, and control passes to the next step.
. 8.3.15 Automadc Actuator Ra.t to Track Zero (Ree.1 Function)
Upon system start. the Seek Function Initialization (paragraph 8.3.4) sets the Recal Aag (RCFLG) to indicate that
the actuator arm has not
been calibrated to track zero and to provide for a ten revolution delay before Recal. The
Motor Status Monitor (paragraph
8.3.7) checks to see of the unit has been recalibrated. If not. it checks the disk
revolution period to
see if the disk is running fast enough.
If it is. RCFlG is incremented once each time the Motor StatuI Monitor is entered. After ten entries. i.e., ten disk
revolutions. RCFLG
is incremented to zero. If it is not, the routine Is exited. If it is, the actuator is stepped outward
512 steps or until track zero is found.
The Actuator Lube Unstick Routine
is enabled by setting the LUBE flag (paragraph 8.3.14) and control pasSes to
the Write Current Control Function. .
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