Control Data Cyber 170 Series Operator's Manual page 256

TAPE UNIT OPERA TION
NOS supports unit models 657 and 667 for 1/2-inch 7-track magnetic tape and models
659 and 669
~or
1/2-inch 9-track tape.
All models haVe a unit select switch at the top of the cabinet. This switch has positions
o
to 7 and is used to identify the unit. Each unit that is on should have a unique number
but once this switch is set, it can be ignored during operation. It lights red when the
unit is reserved on a data channel.
The system and the operator identify a unit by its EST ordinal as shown in the E dis-
play. Ins talla tions usually configure the system so the last digit of an ordinal for a
tape drive is the same as the unit select switch setting, making it easier to equate the
two.
657 AND 659 TAPE UNITS
The following switches and indicators on 657 and 659 tape units are explained below.
Figure D-6. 657 and 659 Tape Unit Switches and Indicators
POWER When power is applied to the unit, this switch is lighted.
WRITE ENABLE Indicates presence of a write ring on a reel.
READY This switch places the unit under processor rather than manual
control. It is lighted when ready status exists.
CLEAR When CLEAR is pressed, it initiates a master clear of processor
control and places the unit under manual control. It is lighted
when selected.
REWIND When REWIND is pressed, the tape rewinds from the takeup
reel to the supply reel, stopping at the load point. It lights
during tape motion.
REVERSE When REVERSE is pressed, the tape begins to
move
backward
onto the supply reel, stopping when the CLEAR switch is pressed
or the load point marker is sensed. It lights during tape motion.
200
Pressing this switch selects a recording density of 200 bytes per
inch; it is lighted when selected.
556 Pressing this switch selects a recording density of 556 bytes per
inch; it is lighted when selected.
800 Pressing this switch selects a recording density of 800 bytes per
inch; it is lighted when selected.
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