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ADDCOM(4)                BSD Kernel Interfaces Manual                ADDCOM(4)

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 proba-
     bly 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 sub-
     devices.  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
     com(4), intro(4), isa(4)

HISTORY
     OpenBSD support for addcom devices first appeared in OpenBSD 3.0.

BSD                             April 23, 2017                             BSD