Control Data 1700 Maintenance Manual page 24

WRITE DATA, STATION 4
When a Write Data operation is requested, the Common Synchronizer must connect
the A Register output data lines to the designated station. The data on these
lines will transfer to the output device where a write operation is performed.
The following example assumes a Write Data to the paper tape punch.
With a Write Data request on station 4, the following initial conditions exist
in the Common Synchronizer:
(1) 3-B17-23 and -27 output logical ones.
(2) 3-B17-26 outputs a logical "0".
(3) 5-B14-22,24, and 6 all output logical ones.
(4) 5-B14-7 outputs a logical "0".
The Write Data signal outputs of 3-B17-23 and 3-B17-27 are sent to the two
controllers capable of write operations, (teletypewriter and punch). The station
4 translation (page 5) along with the Write Data signal informs the punch
controller that a write operation is being requested. If the punch can accept
the data, it will do so and send a Reply to the Common Synchronizer. If the
punch cannot accept the data, no data transfer will occur and a Reject will be
sent to the Common Synchronizer. The effect of Reply or Reject upon computer
operations is the same as for the function operation.
Once data has transferred to an output device, the device goes into a Busy
condition while the data is processed. During this Busy state f~rther data
transfers are prohibited. Once the data word has been processed, a Not Busy
condition will exist allowing another data transfer from the computer.
1-13