Control Data Corporation CYBER 170 Series Operator's Manual page 291

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WRITE DISABLE
No switch function. illuminated, it indicates the
absence of a write enable ring in the right tape
reel. Disables the write circuitry and conditions
the tape unit to accept only read functions.
HI DEN/LO DEN
No switch function. HI DEN illuminates in phase
mode for 9-track tapes or in 800 bpi NRZI mode
for 7-track tapes. LO DEN illuminates in 800 bpi
NRZI mode for either 9- or 7-track tapes or for
556 bpi NRZI mode for 7-track tapes.
Unit Number Display
Shows tape unit number in octal numbers, 00 to 17.
UNIT NO/HOLD REL
Two-position rocker switch used to assign tape
unit number. Pressing UNIT NO causes that
portion of the switch to light, indicating that a
hold status is being sent to the tape controller
unit. Numbers shown on the unit number display
advance until UNIT NO is released. Pressing
HOLD REL removes the hold status on the tape
unit; the indicator light turns off.
677 AND 679 TAPE UNITS
The functions of the switches and indicators on the 677/679
tape unit (figure D-5) are described below. Switches with
alternate actions are described in terms of (1) first and (2)
second action.
POWER ON/OFF
(1) Activates power circuits, places tape unit in
power-up status, and lights indicator. (2)
Deactivates power circuits, places tape unit in a
power-down status, and turns off indicator light.
LOAD/REWIND
(1)
Initiates load operation (reel-to-reel contact,
thread and set loops). (2) When unit is loaded but
not ready, initiates rewind to loadpoint operation •
START/READY
Places tape unit under system control via tape
control unit. Light indicates unit is in ready
status awaiting system activity. Light
extinguishes when a fault condition is detected.
REWIND UNLOAD
If the unit is loaded but not ready, the tape is
rewound to BOT and the tape uni t is unloaded. If
present, the cartridge closes. The reel latch and
window open.
If the unit is not loaded or a fault has been
detected, the window lowers.
60435600 L
CLEAR/WINDOW UP
When tape unit is on-line, negates READY
condition and stops tape motion.
If
window is
down, it is raised. Load check is reset if
applicable.
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NOTE
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Do not use this control during
system operation.
POWER FAULT/LOAD·FAULT
No switch function. Indicates a power fauIt
occurred or a fault occurred during the load
procedure.
SELECT
No switch function. Light comes on when tape
unit is selected by tape control unit.
BOT/EOT
No switch function. illuminates when loadpoint
marker or end of tape marker is detected,
depending upon tape motion direction.
WRITE DISABLE
No switch function. "illuminated, it indicates the
absence of a write enable ring in the right tape
reel. Disables the write circuitry and conditions
the tape unit to accept only read functions.
TAPE UNIT OPERATION
All tape units can handle cartridge-contained tape reels or
standard 10-1/2-inch supply reels. Smaller noncartridge
reels can be used, but they must be threaded manually.
The take-up reel" on left side is a vacuum hub assembly
permanently attached to the tape unit.
When a load sequence is initiated, the cartridge-contained
tape reel programs the tape unit to thread tape and load
loops into the vacuum columns automatically. Internal
delays control the" timing of the load/thread operation. If a
fauIt is detected during a load attempt or if a successful
load is not achieved, one automatic retry is executed. At
the expiration of the automatic load attempt, the tape unit 9
automatically stops and lowers the power window. When II
standard reels are used, the automatic retry is inhibited
and operator action is required.
The power window of the tape unit is activated by control
logic circuits and is raised or lowered in response to LOAD
and UNLOAD commands initiated by you. Initially, when
the POWER switch is pressed, the window lowers, allowing
access to the tape deck. An interlock protection switch
prevents power window operation when the front access
door is open.
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