[linux-elitists] Introducing Myself

Brian McGroarty brian@mcgroarty.net
Wed Jan 7 10:43:28 PST 2004

On Wed, Jan 07, 2004 at 09:31:05AM -0800, Teh Entar-Nick wrote:
> begin  Ben Woodard  quotation:
> > This might be a stupid question but does anybody know if BASIC is still
> > hiding there in our BIOS. I don't remember how to get into it and
> 	It was only ever in actual IBM PCs and XTs.  IBM charged a
> pretty penny to license the ROM BIOS to other vendors, and I don't
> think even Compaq bothered with it.

Bingo. Whether BASIC referenced ROM or loaded code was the biggest
difference between the DOS MS gave to IBM and the DOS MS gave to
everyone else.

BASIC existed in the PC, XT, PCjr, AT, Convertible, and through the
PS/2 line. Modern IBM-built or -branded PCs don't have it.

ROM basic was launched on interrupt 0x18. If you really want to test
if your BIOS supports basic, boot from a DOS disk and run DEBUG.COM,
and punch in:

a              (assemble at 0x100)
xor ax,ax      (clear ax register)
int 18h        (fire off interrupt 18)
               (blank line)
g              (execute at 0x100)

The BIOS should explicitly tell you that no BASIC is present (if it
isn't). I won't begin to guess what happens if you try this from
within Windows. If someone's feeling brave, maybe they can test and
see if that bit of legacy actually exists in the NT VM, but I've got
too many apps up to afford a crash right now.
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