Control Data Corporation CYBER 170 Series Operator's Manual page 293

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UNLOAD AND REEL REMOVAL
The REWIND/UNLOAD switch rewinds and unloads a tape
when the tape unit is off-line.
It
is not necessary to use
this switch during normal operation, since the operating
system controls tape movements. The operator command
UNLOAD,xx. logically unloads a tape that is physically
loaded but not in use.
After unload is initiated, the tape rewinds at high speed
until the load point marker is detected. A downshift to
normal operating speed occurs at load point detection. The
leader length unwinds completely from the left onto the
right reel and simultaneously, the cartridge closes and the
power window lowers. The automatic hub, if applicable,
releases the right tape reel for removal from the tape deck
area.
EMERGENCY STOP
Operator action of the CLEAR switch terminates the
operation in progress. Switch activation is effective in
either off-line or on-line mode. Pressing the CLEAR
switch one time, while in rewind mode, causes the unit to
down shift to normal tape speed; 200, 150, or 100 inches
per second. A second activation terminates the rewind
operation and causes the tape movement to stop.
REFLECTIVE MARKERS
The load point and end-of-tape markers are placed near the
beginning and end of the tape to enable sensing of the
usable portion of the tape by the photocells. Adhesive
material on one side of reflective material secures the
markers to the tape. Vaporized aluminum deposited on the
material creates a highly reflective surface.
The markers, approximately 1.2 inches long and 0.2 inch
wide, are placed on the uncoated side of the tape. The
uncoated side is the underside of the tape when mounted on
the tape deck. The end-of-tape marker is placed on the
edge of the tape nearest the tape deck; the load point is
placed on the' outer edge of the tape. The 667/669 tape
unit is capable of loading tapes with load point markers
located up to 40 feet from the beginning of the tape. The
677/679 tape unit is capable of loading tapes with load
point markers located up to 26 feet from the beginning of
the tape. Recommended distance is 10 to 18 feet.
844 DISK STORAGE UNIT OPERATION
To ready an 881 or 883 disk pack' on the 844 Disk Storage
Unit:
1.
Press the main cover latch and lift the main cover
of the unit. Remove the base of the pack
container so that the pack is held only by its cover.
2. Using its cover as a handle, place the disk pack
slowly over the spindle until it engages the spindle
drive unit. Turn the disk pack cover clockwise to
a full stop position. At this point, the cover is
released from the pack and can be lifted off.
tThis switch is used for maintenance only.
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3. Close the main cover making sure that it latches.
If the cover is not securely latched, the dust cover
interlock remains open and prevents power
application.
4. Press the START switch to apply power to the
unit. When the disk pack is at operating speed,
the READY indicator lights. The disk storage unit
is now ready for operation.
Before unloading an 881 or 883 disk pack from the 844 Disk
Storage Unit, examine the mass storage status (E,M.)
display. A disk pack can be physically unloaded only if the
global unload status (N) is displayed on all machines
accessing the disk pack. Refer to the description of
UNLOAD in section 3.
To unload:
1.
Press START switch to turn off indicator light and
stop unit.
2. When disk pack has stopped spinning, press main
cover latch and lift main cover.
3. Place a disk pack cover over loaded disk pack so
that it engages spindle. Turn counterclockwise
until spindle clicks, and lift cover and disk pack
from unit. Replace base of pack container.
885 DISK STORAGE UNIT OPERATION
The functions of the switches and indicators on the 885
Disk Storage Unit (figure D-6) are described as follows.
Switches with alternate actions are described in terms of
(1) first and (2) second action.
CHAN I ENABLE
or
CHAN II ENABLE
(1) Enables communication between drive and
controller attached to associated drive. channel;
lights indicator. (2) Disables communication
between drive and controller attached to
associated drive channel; turns off indicator light.
I
RSVD
or
II
RSVD
No switch function. Lights when controller
reserves associated drive channel.
SYST
MAINTt
(1) Enables fault checking and manual seek tests;
lights indicator. (2) Disables fault checking and
manual seek tests; turns off indicator light.
SELECT
& RSVD
No switch function. Lights when reserved drive
channel is active .
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