Control Data 1700 Maintenance Manual page 78

The logical "1" from 43-C03-9 starts a 30 msec time delay on Page 47. If this
delay times out, it means the hopper is empty and no more cards are to be read.
The logical zeros from 43-C03-l2 and -10 prevent the controller from reacting to
any more clock pulses.
If the card leaving the read station is not the last card to be read, another
one will enter the read station before 30 msec have elapsed since the Read
Station Empty signal was generated. As the old card leaves the read station,
pressure rollers are raised. In the raised position, these rollers cause a
ground to appear at 43-B04-l0. With the arrival of clock pulses (clock pulses
are generated until column 82), the AND gate at TP ~ (Z33 module, page 43)
is satisfied. This generates a 3.5 msec stop pulse to the excapement control
circuit in the card reader -- a requirement to insure that the incoming card is
positioned squarely into the read station. Since these Stop pulses are only
momentary, they do not, in fact, stop the card reader operations.
As soon as a new card enters the read station, the Read Station Empty signal
(43-C03-8) drops, causing card movement to continue through the read station.
The first Field pulse will appear, followed by the Clock pulse for column 1. This
will cause Field 1 and Field 2 FFs to set (page 41), the timing chain to cycle,
information to transfer from column 1 to the Data Register, the Stop FF to set
and the Motion FF (page 41) to clear, allowing the card to stop on column 1.
When the card stops, a Ready Status is generated and the controller awaits a
Start Motion Function to continue. The previously explained operations repeat
for the reading of this card.
If the card leaving the read station is the last card, the 30 msec delay (47-B05
-2) will time out sending a RSE
+
30 msec signal to 43-B04-l8. This will
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