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TABLE 3-3.
COMMANDS (CONT'D)
Command
Definition/Function
Reset Diagnostic
Mode
(ROM)
Tag
15
Tag 16, 17
Shift Positioner
Out (SPO) Tag
18
Shift Positioner
In (SPI) Tag
19
Advance Read
Clock (ARC)
Tag
lA
Retard Read
Clock
RRC
Tag
1B
Set Diagnostic
Mode
(SOM)
Tag 1E
83318200
B
I
1.
A
control command.
2. Resets diagnostic operations (Tags lE or IF) and places drive in
normal mode.
3. The drive performs an RTZS (refer to Recalibrate Tag
12).
These tags are recognized and acknowledged by the drive but initi-
ate no operations.
1. A control command.
2.
This is used for data retry and error recovery.
3.
It causes the positioner
to
move the read/write heads
400
~in
away from the spindle unless Shift Positioner In (Tag
19)
was
active in which case it would cause the heads to return to the
track centerline.
In either case the drive generates a
10
ms
Positioner Busy signal.
4. The Offset condition is reset and the positioner returned to the
track centerline by any of the following:
•
Device Initialize Signal (DIN)
•
Return to Centerline (Tag
30)
•
Shift Positioner In (Tag
19)
•
Any Seek Command (however the seek is not performed)
•
Loss of On Cylinder
1. A control command.
2.
Same as Shift Positioner
OUt
(Tag
20)
excepe that the heaas are
offset
400
~in
towards the spindle and Shift Position OUt replaces
Shift Position In as a reset condition.
1.
A control command.
2.
Used during data recovery it moves the Read Data strobe to the
early position of the data window (about
8
ns earlier than
nonnal).
3. The function is reset by a Recalibrate (Tag
12)
or Retard Read
Clock (Tag lB).
1.
A control command.
2.
The same as Advance Read Clock (Tag
lA)
except that it retards
the Read Data strobe by about
8
ns.
3.
Reset by a Recalibrate (Tag
12)
or an Advance Read Clock (Tag
lA).
1. A control command.
2.
Places drive in diagnostic mode and sets bit
7
(Device in Diag-
nostic Mode) of Summary Status Byte.
3. This command initiates no function in drive unless Set Diagnostic
Escape' (Tag IF) is also received.,
4. Drive returned to normal operation by a Reset Diagnostic Mode
(Tag ls) or by the Device Initialize line going true.
3-29
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