Ref: 08040023
Title: Texas Business Pro Compatibility with 3+
Date:  07-20-88

Copyright 3Com Corporation, 1991.  All rights reserved.

Date: 4-13-87
The version of Texas Business Pro we saw shipped in the middle of
last year didn't work.  The reason is that the TI BIOS considers
calls to an uninitialized vector as errors and traps them. When
NB starts in 3+, it calls its vector (5C) to determine if it is
already loaded. The TI Bus Pro hangs here with an error message.

I was able to get it to work by writing a TSR program that
changed all the default vectors to point to a do-nothing
interrupt handler in the program, thus avoiding the BIOS trap.
The machine could be made to run by putting this program's name
in the beginning of your autoexec.bat file. After this is seemed
to work ok, both as a server and a workstation, but it wasn't
tested very extensively.

Tech Notes: The program has, hard coded in it, the BIOS vector
value that I found in the machine I saw (F000:9A8A). It looks for
this value and changes it to point to the new do-nothing handler.
This original BIOS loaded vector could change in some other BIOS
version. To see if the machine has the same vectors, boot it to
DOS, load debug, type 'd 0:170'. Most of the values in this area
should be '8A 9A 00 F0'. If not, you may need to modify the
values in the program to match what you find and reassemble. Of
course, try to load it as a workstation first, and see if it
comes up. They could have changed the way they handle default
vectors by now.

