COM(4)                OpenBSD Programmer's Manual (Alpha)               COM(4)

NAME
     com - AlphaStation serial communications interface

SYNOPSIS
     com0 at isa? port "IO_COM1" irq 4
     com1 at isa? port "IO_COM2" irq 3

DESCRIPTION
     The com driver provides support for NS8250-, NS16450-, NS16550- and
     ST16650-based EIA RS-232C (CCITT V.28) communications interfaces.  The
     NS8250 and NS16450 have single character buffers, the NS16550 has a 16
     character buffer, while the ST16650 has a 32 character buffer.

     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, or 115200, or any other baud rate which is a factor of
     115200.

FILES
     /dev/ttyC0

     /dev/ttyC1

DIAGNOSTICS
     com%d: %d silo overflows  The input ``silo'' has overflowed and incoming
     data has been lost.

     com%d: weird interrupt: iir=%x  The device has generated an unexpected
     interrupt with the code listed.

SEE ALSO
     ast(4), rtfps(4), tty(4)

HISTORY
     The com driver was originally derived from the HP9000/300 dca driver and
     is currently under development.

BUGS
     Data loss is possible on busy systems with unbuffered UARTs at high
     speed.

     The name of this driver and the constants which define the locations of
     the various serial ports are holdovers from DOS.

OpenBSD 3.0                     August 6, 1993                               1
