NAME
addcom —
multiplexing serial communications
interface
SYNOPSIS
addcom0 at isa? port 0x108 irq 5
com* at addcom?
DESCRIPTION
The addcom driver provides support for
Addonics FlexPort 8/S (and probably FlexPort 4/S) boards that multiplex
together up to eight (or four) EIA RS-232C (CCITT V.28) communications
interfaces.
Each addcom device is the master device
for up to eight com devices. The kernel
configuration specifies these com devices as slave
devices of the addcom device, as shown in
SYNOPSIS. The slave ID given for each
com device determines which bit in the interrupt
multiplexing register is tested to find interrupts for that device. The port
specification for the addcom device is used to
compute the base addresses for the com subdevices.
The port for the interrupt multiplexing register is fixed, so it is doubtful
that more than one addcom can be used in a
machine.
FILES
- /dev/tty??
SEE ALSO
HISTORY
OpenBSD support for
addcom devices first appeared in
OpenBSD 3.0.