Printed 11/19/92                   Page 1

SDUART(7)           RISC/os Reference Manual            SDUART(7)



NAME
     sduart - Signetics Dual Asynchronous Receiver/Transmitter

SYNOPSIS
     On-board serial port driver

DESCRIPTION
     This driver handles the on-board serial ports.

     Each line attached to the sduart port behaves as described
     in tty(7).  Input and output for each line may independently
     be set to run at any of a number of speeds; see tty(7) for
     the encoding.

CAVEATS
     Even numbered ports (ie tty0 and tty2) do not support RS-232
     control signals.  Therefore these cannot be used reliably
     with modems.  On M120/180 these are DTE ports, on M1000/2000
     these are DCE.

     Odd numbered ports (ie tty1 and tty3) offer some support of
     RS-232 signals.  This support is limited to DCD recognition,
     and the ability to raise/lower DTR and RTS.  Also, on these
     ports, DCD, which should come in on pin 8, comes in on pin
     5.  Therefore a special cable is required in order to jumper
     pin 8 on the modem side to pin 5 to the computer side, and
     therefore get proper behavior in regards to DCD.  These odd
     numbered ports are DTE on all machines.

     The default speed setting for /dev/tty0 is continuously
     updated to the last speed set on that port.  This causes the
     speed of the port at the next open to be whatever speed was
     previously set on that port.

FILES
     /dev/tty[[0-3]

SEE ALSO
     tty(7)
     Signetics SCN2681 Dual Asynchronous Receiver/Transmitter
     Product Specification














                        Printed 11/19/92                   Page 1