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11.1
CHARTS
Systems pages 7X. 01.02 through 7X. 06.02 contain charts showing pluggable unit
locations, cable connectors, fuses, and relays.
11. 2
SELECT AND READY 75. 01
A tape unit is ready for selection when the tape has been loaded into the columns,
the reel-d oor interlock is closed, the unit is not rewinding, and the start key has
been pressed.
These conditions are indicated by the plus status of the lower input to
AND circuit A12.
The center leg of AND circuit A12 goes down for 20ms when the
load point is sensed at the completion of a rewind operation.
change in status from a reverse stop to a forward stop before the unit can be ready.
The third input is up when the external select line corresponding to the setting of
the select switch is up.
line.
This line must be plus in order to operate the tape drive from the control unit,
with the exception of the tape-indicator control.
The select line is plus when the external select line corresponding to the setting
of the select switch is up, regardless of the ready condition.
the select light to come on through the IL , and also conditions the tape-indicator
control.
11.3 READ-WRITE STATUS 75.02
Set Read Status
"Set read status" is externally generated. It is combined in AND circuit C5 with
"select and ready" and the resulting positive shift turns off the read-write-status
trigger.
This trigger indicates a read or write status of the tape unit. If the unit is
already in read status, the trigger is off.
trigger combines with "select and ready" in AND circuit A35, to bring up "select,
ready and re a d ," This response is returned to the control system indicating that a
tape unit is selected, ready, and in read status.
Set Write Status
"Set write status" is externally generated. It combines with "select and ready"
in AND circuit C24, and the resulting positive shift turns on the read-write-status
trigger if it is off.
The right output of this trigger is combined with "not file protec
tion" in AND circuit E25 and the result is combined with "select and ready" in E18 to
produce "select, ready and w rite." This response is returned to the control system
indicating that a tape unit is selected, ready, and in write status. Whenever the out
put of AND circuit E25 is plus, the write inverters conduct through the write heads,
and the erase head conducts.
11.0
MISCELLANEOUS
The output of AND circuit A12 becom es the select and ready
The left output of the read-write status
36
This allows time for the
The select line causes
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