multiplexing serial communications interface
addcom0 at isa? port 0x108 irq 5
com* at 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.
OpenBSD support for
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
The port for the interrupt multiplexing register is fixed, so it is doubtful
that more than one
addcom can be used in a
devices first appeared in OpenBSD 3.0.