Control Data Corporation 6000 Series Reference Manual page 28

A scheme for encoding and decoding blocks of data by generating a 12-bit cyclic code
is used. This provides the following error detection capabilities:
1) Any odd number of errors
2} All error bursts of 12 bits or less
3) 99. 5 percent of all error bursts of 13 bits
4) 99. 98 percent of all error bursts of 14 bits or greater.
An error burst is any pattern of errors whose length is the number of bits between
the first and last errors of a transmission. The cyclic code is one of the most
effective and economical error detection techniques
for
serial transmission presently
known.
A maximum line efficiency of 99. 4 percent can be achieved when the length of the data
block is 341 12 -bit words.
Testing
Data transmission and reception may be checked without computer control through a
control panel on the DSC. The control panel generates a data block consisting of a
sync word, a 12-bit word, and a cyclic word. Checking data through the DSC saves
valuable computer time.
Response Circuit
The DSC Response circuit enables the computer to check whether the remote station
recognizes the sync word. The receiving DSC automatically returns a response code
to the transmitting DSC when the receiving DSC detects a sync word. This allows the
transmitting computer to determine if communication has been established. Response
code transmission is simultaneous with data reception.
Rev. A
3-15