ZS(4)

NAME
zs, zstty - Zilog 8530 (ZSCC) Serial Communications Controller

SYNOPSIS
zs* at ioasic0
zstty* at zs?

DESCRIPTION
The zs driver provides TTY support for the two Zilog 8530 Dual UART chips found on DEC 3000 systems. On these systems, two of these serial interfaces are hardwired for use by the keyboard and mouse. Only the second interface of each zs controller can be used as a regular serial port. The zstty interfaces provide RS-423 and RS-232 serial ports for general purpose use.

The zs driver supports all of the standard tty(4) ioctl calls. The status of the DTR, RTS, CTS, and DCD signals can be queried with the TIOCMGET command but, due to limitations in the hardware, only the DTR and RTS signals can be modified with the TIOCMSET, TIOCMBIC, and TIOCMBIS ioctl(2) commands.

Input and output for each line may be set to any baud rate in the range 50 to 38400.

FILES
/dev/ttyB[01]
/dev/cuaB[01]

DIAGNOSTICS

zs*: 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.

zs*: 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
intro(4), ioasic(4), tty(4)