6300 add'l serial port

[Peter Fales]

> I "just happen" to have this antiquated-but-still-servicable IBM serial port
> card in my collection of random hardware.  I was wondering if this could be
> used to add a second serial port to my 6300 - I've got three (!!!) RS232
> devices hanging off of the one port, and I'd like to go to 6 :->.  Seriously,
> though, does anyone know what the jumper settings are to use this beastie
> as a second comm port, and if it will work in my pc?
> Thanx 2 million (inflation, ya know...)
>                               \scott

I added an IBM compatible serial port as the second port on my 6300.  Since
it came from a third party vendor, I don't know how much it looks like
the real IBM animal, but it took some very minor solder surgery (add one
jumper) to get it to work.  Details follow:

The board actually supports two serial ports.  Port A is connected to
the DB-25 that comes out the back of the system.  Port B is designed to
be brought out on a cable.  The switches allow port A to be addressed either
as COM1 or an "alternate address" and port B as either COM2 or another
"alternate address."  They never thought of the case where port A would
be used as COM2, but this was remedied by soldering a jumper from the COM2
chip select on port B to the chip select on port A and setting the dip
switches to this did not cause a conflict.  The existing dip switches
allowed the appropriate interrupt request lines to be selected.

I can supply more details, but unless your board is exactly like mine,
you probably need a schematic of the serial board to make it work.

Peter Fales
ihnp4!ihlpl!psfales