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.