S10-320, DUAL SERIAL CARD, LGS, GMI6C550

ISA Controller Card with 1 or 2 serial ports

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It is awfully hard finding information on this card on the internet. So I tried messing a bit with it myself. These are the results:

• As I bought that card, I was told that I could upgrade it to a second serial port. I guess if you fill the free IC slots you can connect another serial cable (with the connectors top-right). I never upgraded, so I don't know what ICs are needed.
• JP2 is for setting the IRQ of the serial ports. the upper one is for the first port (on-board), the lower one is for COM B.
  I didn't try setting both ports to the same IRQ but it should work. (COM3 and COM1 often share an IRQ, too)
• With JP1 you can set the addresses of the ports. If a jumper is covering the center and the right pin, that address is to be used for COM A, if a jumper is covering the center and the left pin, that address is to be used for COM B.
  That way you can't have an I/O conflict on the card alone. (Of course you can have an I/O conflict with other hardware in your system).
  I didn't try giving one port multiple I/O addresses. If you try and have some interesting information, drop me a line!
• I disabled the second port (so my OS doesn't find a missing port) by simply removing all jumpers for COM B
• The serial port is a rather recent one (should be 16550A or something). I bought it especially to improve modem speed.