BISYNC

type of binary-coded synchronous data communication used primarily in networks based on mainframe computers

Binary Synchronous Communication (BSC or Bisync) is an IBM link protocol, announced in 1967 after the introduction of System/360. It replaced the synchronous-transmit-receive (STR) protocol used with second generation computers. The intent was that common link management rules could be used with three different alphabets for encoding messages. Six-bit Transcode looked backwards to older systems; USASCII with 128 characters and EBCDIC with 256 characters looked forward. Transcode disappeared very quickly but the EBCDIC dialect of Bisync still has very limited use in the 2000s.
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Binary Synchronous Transmission

BINARY SYNCHRONOUS COMMUNICATIONS (PROTOCOL). BISYNC