Binary Synchronous Communication (
BSC or
Bisync) is an
IBM character-oriented, half-duplex
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 character encodings for 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 and USASCII dialects of Bisync continued in use.