NAME
rtfps —
multiplexing serial
communications interface
SYNOPSIS
rtfps0 at isa? port 0x1230 irq 10
com2 at rtfps0 slave 0
com3 at rtfps0 slave 1
com4 at rtfps0 slave 2
com5 at rtfps0 slave 3
DESCRIPTION
The
rtfps driver provides support for IBM RT PC boards that
multiplex together up to four EIA RS-232C (CCITT V.28) or RS-422A
communications interfaces.
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 the 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)
HISTORY
The
rtfps driver was written by Charles Hannum, based on the
ast driver.
BUGS
The
rtfps driver is unlikely to work on non-EISA and non-PCI
machines. The ISA bus only asserts 10 I/O address lines, and this is not
enough.
Even on EISA and 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.