🚀 go-pugleaf

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In article <1991Apr26.160753.4754@midway.uchicago.edu>, valley@gsbsun.uchicago.edu (Doug Dougherty) writes...
>dj@ctron.com (DJ Delorie) writes about the 286 LOADALL instruction:
> 
>>There is such an opcode, and Microsoft used it in OS/2 for 286
>>machines.  From what they told me, they had a really hard time getting
>>Intel to tell *them* about it.  They used it primarily to set up the
>>hidden portion of the segment registers in real mode to access memory
>>above 1M.  It is *not* available on the 386, and may not exist on new
>>286 designs, or on non-Intel 286's.  It's very non-portable, also.
..
>uses it (LOADALL) in their systems (an operating system, no less) that that
>pretty much legitimizes it.  Can you imagine some clone 286 manufacturer
>having to admit that their chips won't run OS/2?

My new '486 motherboard has a set of options in the CMOS chipset 
configuration regarding exactly that. You can reconfigure the chipset to 
honor the LOADALL memory access if you want to run OS/2, or you can disable 
that feature (and gain about 1k of main memory, I think).

It's hard to imagine that some undocumented feature can evolve into 
something so significant that chipset manufacturers are changing their 
PALs...

>--
> 
>	(Another fine mess brought to you by valley@gsbsun.uchicago.edu)

___Samuel___
_________I_claim_and_accept_sole_responsibility_for_the_above._SjG.____________
<goldstein@aerospace.aero.org| "Real Mode is required primarily to setup the
  There's no need to cure a  |  processor for Protected Mode operation."
   C8-H10-N4-O2 addiction.   |	80386 Hardware Ref. Man., p. 4-174, Intel.