AT&T 6300+ ROM BIOS problem

[Jim Rosenberg]

In article <54810 at linus.UUCP> bwk at mbunix (Barry Kort) writes:
> [...] responds to my earlier plea for help on DigiTalk
>SmallTalk V/286, which does not run on my AT&T PC 6300 Plus:

>I'm still looking for an existence proof that V/286 can be made to
>run on the 6300 Plus, before I continue with more exploratory
>neurosurgery on the motherboard.

I have a feeling you may be totally out of luck.  This question came up once
before, & I don't remember any happy-ever-afters.  The problem is most likely
that ST/V runs in protected mode.  Bless their leetul hearts, the designers at
Intel figured that protected mode was the duckiest thing for multitasking in
the history of the universe, that multitasking was for adult operating
systems, that adult operating systems need security, ergo to be able to go
from protected mode to real mode in an adult operating system would always be
a certifiable no-no:  SO THEY MADE NO WAY TO DO IT!  Now ST/V 286 runs
"native" in protected mode, but must get back to real mode to access DOS.
Therein lies the rub.

There *is* a way to get from protected mode back to real mode, but it will
make your hair stand on end.  It literally involves *RESETTING* CPU (no
kidding!)  but first there is some fancy footwork so that on "boot" the system
knows that this is not a "real" boot.  I believe this fancy footwork involves
writing some status stuff to the CMOS, *and* (I'm not clear on the details
here) writing something out to the *keyboard controller*.  (We're resetting
the whole damn CPU remember ...)

If your machine does not look like an AT, walk like an AT, quack like an AT,
and lay AT eggs then this whole protected --> real mode dodge is almost
certain not to work.  The 6300+ is a hybrid beast which I believe most
certainly *DOESN'T* look like a regulation AT in terms of CMOS & keyboard
controller.  The problem is much more difficult than simple BIOS
compatibility.

Your only hope is to find somebody who's got a way to get protected mode
software to work.  But don't get your hopes up.  You may simply have to face
the fact that ST/V just plain won't run on the 6300+.  If Digitalk does not
have a solution you are most likely out of luck.
-- 
 Jim Rosenberg
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