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
Thertfps 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
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.