On Sun, 2 Jan 2000 15:33:35 +0100, "Boudewijn"
<newsgr...@bdijkstra.tmfweb.nl> wrote:
Bill Hayles <bill...@ctv.es> schreef in
berichtnieuws
3857030c.28698...@news.ctv.es...
There was only one real difference
between MS and PC flavours of the
same version, and it had to do with a
hardware difference between IBM
and non IBM machines.
As a clue, I'll ask this teaser:
Very often, if you try to boot a
computer which has no disks, either
hard or floppy attached, you will see
the message:
ROM BASIC NOT FOUND. SYSTEM HALTED.
Why doesn't it just say "NO DISKS
FOUND?"
Apparently we don't know, so please tell
us.
I'd forgotten all about this one! OK, kiddies, sit down and make
yourselves comfortable while Grandpa Bill tells you about the pioneering
days, when dinosaurs roamed the earth, windows were something you looked
out of and a desktop was where you kept your papers and pens.
I won't bore you at this stage of the story of how Microsoft got the
contract to supply the IBM PC with an operating system, just suffice it
to say it was called PC-DOS and Microsoft reserved the right to sell
their system to third parties as MS-DOS.
The original IBM PC had an 8 inch floppy disk, a cassette tape drive and
Microsoft BASIC in ROM. When it booted, it first of all looked for a
floppy disk in the drive. If it found it, it booted using the OS on the
floppy disk (usually, but not exclusively, PC-DOS). If the disk in the
floppy disk was not a system disk, it gave the message, familiar to many
of you, I'm sure, "Non system disk or disk error. Press any key to
continue". If there was no disk in the floppy drive, it started the
BASIC interpreter in ROM, in the same way as most other computers of the
era started. From the BASIC prompt, you could load or save programs to
tape or floppy or even write your own. Therefore, the original IBM PC
could start without any sort of system disk.
Although the IBM PC was open architecture, the BASIC ROM chip was
copyrighted. So when the first clones, such as the Compaq, were built,
there was no BASIC ROM chip. These worked with the third party OS
called MS-DOS. This contained a Software BASIC interpreter called
GW-BASIC, which was functionally identical to the IBM ROM BASIC.
However, these clone computers could only start with s system disk. But
the boot code still looked for BASIC in ROM if there was no disk. When
it couldn't find it, it returned the error:
ROM BASIC NOT FOUND. SYSTEM HALTED
Which makes sense now I've explained it.
What is curious is that in the course of building computers I always
test the motherboard and RAM before adding any disk drives, and even
with early Pentiums the message was the same. It's only recently that
boot code has stopped looking for BASIC in ROM!
Felices Fiestas
El inglés loco
Bill Hayles
bill...@ctv.es