multiplexing serial communications
rtfps0 at isa? port 0x1230 irq 10
com* at rtfps?
driver provides support for IBM RT PC
boards that multiplex together up to four EIA RS-232C (CCITT V.28) or RS-422A
device is the master device for up to
devices. The kernel configuration
specifies these com
devices as slave devices of
device, as shown in
specification for the
device is used to compute the base
addresses for the com
driver was written by
, based on the
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.