🚀 go-pugleaf

In <1992Nov9.115520.5893@fct.unl.pt> jpl@antares.fct.unl.pt (Joao Prospero Luis [ps]) writes:

>Marcus Jenkins (marcusj@apricot.co.uk) wrote:
>: I know this may be an FAQ, but I am just a little confused.  Is
>: LOADALL implemented in the 486?  PC Magazine said that it is
>: in all processors from 2-486.  It also said that Microsoft use
>: the instruction in HIMEM.SYS, SMARTDRV.SYS and RAMDRIVE.SYS in
>: MS-DOS.  On the other hand, an instructor from Intel (while lecturing
>: on an i386/486 programming and architecture course) alleged that
>: LOADALL is only there on 286 and earlier steps of the 386.  Does
>: anybody know the REAL answer?  Is there commercial software out
>: there that does use this reserved instruction.  This enquiry is
>: out of curiosity only - I have no intention of putting LOADALL
>: into any of my programs!

>	As far as I know (it isnt that much) LOADALL isnt implemented in
>the 386, but is simulated by some BIOSes. When it traps an invalid opcode

Actually, LOADALL is two different instructions for 286 and 386.
It seems that at least the d0/d1 version of the 386DX has the LOADALL386
instruction. See /pub/pc/infos/loadall*.txt at ftp.uni-duisburg.de for
information on loadall286 and loadall386.
Many 386 BIOSes versions emulate the loadall286 instruction, because it
is used occasionally in some programs (HIMEM uses it, but only when a
286 is detected; there is seperate code for 386 which is used if one is
detected. The loadall386 is by far not so well known.

>it goes to check if it is a LOADALL, if it is it is simulated otherwise
>it does something else (in fact I think it tests some other invalid opcode
>first but I dont remember which). This was confirmed with my AMI BIOS.

>	JPL

>--
>Joao Prospero Luis                 |
>Universidade Nova de Lisboa        | Internet: jpl@fct.unl.pt
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