zsc —
serial communications interface
The zsc driver provides support for Z8530- and
  Z85230-compatible EIA RS-232C (CCITT V.28) communications interfaces. The
  Z8530 has a 3 character buffer, and the Z85230 has a 8 character buffer.
  However, due to limitations in the design of the Z85230, the driver is unable
  to distinguish it from the Z8530 and will not enable any enhanced features of
  the controller.
Input and output for each line may set to one of following baud
    rates; 50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
    19200, 38400, 57600, 115200, 230400, or any other baud rate which is a
    factor of 115200.
The zsc driver was originally derived from the sun3
  zs driver and is currently under development.
Data loss is possible when using high speeds, particularly on older (68020 or
  68030) Macintosh models and on busy systems.