BTW, neither BIOS nor cassette ROM map to low memory--BIOS starts in the
0E0000 range for PS2s, 0F0000 for normal ATs, cassette Basic having a
start of about 0F6000. This might provide some interesting
consequences, as the Linux Kernel maps BIOS with all zeros, the
BIOS being unnecessary to the kernel after the BIOS hands off to the
kernel. So, concievably, Linux COULD remap memory mapped anywhere on
bootup to int 18h cassette BASIC. DOS even used to do this--the Compaqs
never had the ROMs, but still could use BASICA (which made an int 18h
call) by using a specialized diskette that had an image that would be
software mounted to 0F6000-ish. AFAIK nobody's ever touched int 18h, so
it seems possible that anything mapped to 0F6000 for whatever reason
should be still executed on an int 18h, even in a SMP PIII (this is an old
enough legacy that AMD/Cyrix should use it as well, but this is PURE
speculation on my part). This should work even for software mapping, as
evidened by the Compaq behavior (BTW the reason I use Compaq as an example
is that was my first PC-type computer, in 1985--I only found out why we
had to use the special BASIC diskette in my recent studies of XT ROMS,
though...).
On Sat, 13 Nov 1999, Stefan Pettersson wrote:
> On 12-Nov-99 Sam Steele wrote:
> > My PCjr has a BASIC ROM (a slightly modified version that shows off
> > the "advanced grahpics/sound" of the PCjr when you hit escape as soon
> > as it starts), and when booted without a harddrive, my AMIBIOS based
> > K5 says "NO ROM BASIC", so I don't know if the BASIC call has been
> > replaced with the BIOS setup
>
> This is unverified, but
> I think the Basic-hook is still there, untouched.
> But some of the EPROM area reserved for Basic has been used for the setup
> subprograms.
> So we are back to the usual problem, where in the 640 kB should we put or own
> EPROM.
>
>
> --
> Stefan Pettersson Voice +46-70-5933800 Kanard AB
> [EMAIL PROTECTED] ([EMAIL PROTECTED]) Fax +46-221-50180 Vretberga
> finger [EMAIL PROTECTED] for my public key S-732 96 ARBOGA
>
> "What a scary world it must be, for those with no UID:GID" /OZ9ABN
>
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<a href="mailto:[EMAIL PROTECTED]">John Galt </a>
