multiplexing serial communications
hsq0 at isa? port 0x140 irq 10
com* at hsq?
driver provides support for Hostess
) and compatible boards that multiplex together up to four EIA
RS-232C (CCITT V.28) communications interfaces.
device is the master device for up to four
devices. The kernel configuration specifies
devices as slave devices of the
device, as shown in
. The slave ID given for
device determines which bit in the
interrupt multiplexing register is tested to find interrupts for that device.
specification for the
device is used to compute the base addresses
for the com
subdevices (they are equal to port +
ID * 8) and the port for the interrupt multiplexing register (it is equal to
port + 7). More technical details on how the driver works can be found in the
big comment at the beginning of the driver's source code.
Information on setup of card's configuration switches should be taken from
Comtrol Corporation's web site, since the author wrote and tested the driver
only with Hostess-compatible cards.
driver was written by
Denis A. Doroshenko
based on the