Seek Operation; Recalibrate Operation; Behind Home - IBM System/32 Introduction And Maintenance Manual

'2.1.16 Seek Operation
During a seek operation, the track following
signal to the actuator driving circuits is overridden
by signals from the seek controls. A seek is exe-
cuted by activating the drivers to move the actu-
ator at the correct velocity to the specified track.
At the end of a seek, the seek lines to the drivers
are deactivated; this allows the track following
circuits to hold the actuator at the selected track.
Seek control causes the actuator to leave track
following mode, and accelerates the actuator
over a specified number of tracks. Seek control
then drives the actuator at a constant velocity
until it is a specified number of tracks from the
required destination. Then the actuator is decel-
erated and stops at the required destination. At
this point, track following signals take control.
2.1.17 Recalibrate Operation
The recalibrate operation moves the heads across
the tracks into the guard band area, then out to
data track 0 (home).
Recalibrate is initiated:
1. During a normal power on sequence.
2. When an invalid sector identifier
(10)
is
read.
3. After data unsafe is reset.
2.1.18 Behind Home
If the data heads attempt to seek a track that is
farther in than track 0, the seek in command is
dropped. When the heads stop, the actuator seeks
to track 0 and home is indicated.
Servo {
Head
Output
Preamp
r-
2-8
Actuator
1
Pivot
J
Magnet
l~COil
1
6
-.
"
l
J
[
+24 Vdc
,-
- - - - - - -
- - - - l
(Track following
signaL)
\
In Coil
•
Track
Actuator
Out Coil
Following
r----"'
Driving
Circuit
Circuit
Seek Signals
Override Track ..---
_ Following Signals
Seek
Control
I
,
I
I
L - _
_ _ _ _ _ _ _ .J
Disk Drive Circuit on 01A2
%
board}