Control Data Corporation 6000 Series Reference Manual page 13

With both stations active, data is received from the remote station in the following
manner:
1) The local computer selects a DSC for Receive mode.
2) The DSC receives the sync word and returns a response.
3) Each data word received is assembled into a 12-bit parallel word.
4)
The computer samples status-all, and inputs the data word.
5)
When the complete data block is received, the DSC checks the received
cyclic code word against one it has generated.
If
they do not agree, the
DSC sets the cyclic code-error status bit.
The method of communication presented above is the basic sequence, and many
elaborations are possible. Section 3, Operation and Programming, describes these
variations and discusses the signals that control communication between the computer,
the multiplexer, the DSC, and the data sets. Section
3
also describes manual
controls and indicators.
Rev. A
2-5