COM3 with Xenix 2.2.3

[Jukka Reinikainen]

In article <225 at ispi.UUCP> jbayer at ispi.UUCP (id for use with uunet/usenet) writes:
>In article <10119 at cup.portal.com>, MichaelNC at cup.portal.com (Michael Kent Brady) writes:
>> Or try  "mkdev serial"  
>> 
>> Mine allows COM1 thru COM4
>
>I have said it before, I will say it again.  RTFM!!!  Com3 and com4 are only 
>for use on the Sperry IT 286 boxes (I don't know about the 386).  Sperry,
>now known as Unisys, has some special logic on the board to handle com3 and
>com4.  It is not available and will NOT work on any other computer.  Also,

Wrong, Sperry IT is not the only one, I got com3 and com4 working on my
AT-clone which is *not* Sperry IT.  I have com1 and com2 on mother board,
an internal modem as com4 and a terminal line as com3.  Com1 is connected
to my old Racal-Vadic modem and com2 is for MS-Mouse.  Everything works fine.
Im using SCO Xenix version 2.2 and dev.sys version 2.1.3 (I think...).
What did I do?

1. I edited sioconf.c

      My internal modem card can use IO addresses 3f8,2f8,3e8 and 2e8
      which correspond com1,com2,com3 and com4 and IRQ lines IRQ3,IRQ4,
      IRQ5 and IRQ9.

      My 1-port rs-card can be configured as com1-com4, but com3 uses
      IO address 338/IRQ2 and com4 uses 238/IRQ5.

      I added new descriptors to sioconf.c for internal modem: IO 2e8 and
      IRQ5 (IRQ9 cannot be used), board type IBM_BOARD, port count 1,
      minor dev base 12, interrupt poll addr 0, increment 0 and for
      1-port rs-card: IO 338 and IRQ2, IBM_BOARD, port count 1, minor
      dev base 4, interrupt poll 0, increment 0.

2. I edited master

      master file contains information about different devices including
      interrupt vectors used.  Serial (marked sio) devices used originally
      IRQs 3,4,33 and 34.  I tried those my modem card supports: 3,4,5 and 9,
      but config program didn't like IRQ9, so I used IRQ2 instead.  IRQ5
      is used originally for second parallel adapter (centronics), the main
      parallel adapter is connected to IRQ7 so I used this unused IRQ5 for
      internal modem card.  I replaced the original IRQ5 on the pa
      (parallel) line with 0 and replaced the original vector count 2 with
      1.  This 'pa' line can be found in master file like 'sio' line. 
      Interrupt vector count is 4 for 'sio' line.

3. make

      I recompiled all modified sources with make (yes, you need development
      system to do this) and copied the just linked new kernel to the root
      directory (/comx).

4. reboot

      I rebooted my system and to the boot-prompt I entered comx (name of
      the new untested kernel).  Everything worked fine, com1, com2, com3
      and the internal modem as com4 were found.

So, it's not impossible...    :-)
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