MirBSD manpage: rtfps(4)

RTFPS(4)                   BSD Programmer's Manual                    RTFPS(4)

NAME

     rtfps - multiplexing serial communications interface

SYNOPSIS

     rtfps0 at isa? port 0x1230 irq 10
     com* at rtfps? slave ?
     or
     pccom* at rtfps? slave ?

DESCRIPTION

     The rtfps driver provides support for IBM RT PC boards that multiplex to-
     gether up to four RS-232C (CCITT V.28) or RS-422A communications inter-
     faces.

     Each rtfps device is the master device for up to four com devices. The
     kernel configuration specifies these com devices as slave devices of the
     rtfps device, as shown in SYNOPSIS. The port specification for the rtfps
     device is used to compute the base addresses for the com subdevices.

FILES

     /dev/tty0?

SEE ALSO

     com(4), intro(4), isa(4)

HISTORY

     The rtfps driver was written by Charles Hannum, based on the ast driver.

BUGS

     The rtfps driver is unlikely to work on non-PCI machines. The ISA bus
     only asserts 10 I/O address lines, and this is not enough.

     Even on PCI machines, some address conflicts have been observed. On one
     machine, the second port always conflicted with something (though it's
     not clear what) and caused strange results. Disabling the second port in
     the kernel config allowed the other three ports to function correctly.

MirBSD #10-current              August 7, 1994                               1