ZSTTY(4)

NAME
zstty - serial communications interface

SYNOPSIS
zstty* at zs0 (sparc)
zstty* at zsc1 (others)

DESCRIPTION
The zstty driver provides TTY support for Zilog 8530 Dual UARTS.

Input and output for each line may set to any baud rate in the range 50 to 38400 (and higher on some machines).

FILES

/dev/ttya

/dev/ttyb

DIAGNOSTICS
zs0*: fifo overflow
    The on-chip “fifo” has overflowed and incoming data has been lost. This generally means the machine is not responding to interrupts from the ZS chip fast enough, which can be remedied only by using a lower baud rate.
zs0*: ring overflow
    The software input “ring” has overflowed. This usually means input flow-control is not configured correctly (i.e. incorrect cable wiring).

SEE ALSO
scc(4) tty(4)

HISTORY
The zstty driver was derived from the sparc zs driver supplied with 4.4BSD.

BUGS
The old Zilog 8530 chip has a very small fifo (3 bytes?) and therefore has very strict latency requirements for the interrupt service routine. This limits the usable baud rates on many machines.