[CCTECH] Interesting tidbit on 6502

From: J.C. Wren <jcwren_at_jcwren.com>
Date: Fri Jun 7 10:00:09 2002

        Why don't you learn that you don't always know what you're talking about?

        Indeed, the first step level of the 6800 had an undocumented opcode that
results in 3 particular transistors turning on that connected Vcc to GND.
The damage caused by these three transistors shorting damaged the silicon in
the immediate area, rendering the CPU useless.

        But since the shop I worked for only flamed out 2 Sphere-II 6800 CPUs
before the Motorola FAE defined the problem and gave us new parts, it
probably didn't really happen, since you said it's fiction.

        --John

-----Original Message-----
From: cctalk-admin_at_classiccmp.org [mailto:cctalk-admin_at_classiccmp.org]On
Behalf Of Richard Erlacher
Sent: Friday, June 07, 2002 10:16
To: cctalk_at_classiccmp.org
Subject: Re: [CCTECH] Interesting tidbit on 6502


It's crap like this that causes the confusion that Steve pointed out.

Why can't we keep some distance between fact and facetious fiction for the
benefit of those whose knowledge is largely semantic?

Dick

----- Original Message -----
From: "J.C. Wren" <jcwren_at_jcwren.com>
To: <cctalk_at_classiccmp.org>
Sent: Friday, June 07, 2002 7:26 AM
Subject: RE: [CCTECH] Interesting tidbit on 6502


> This only occurred in the very first step level of the 6800 released,
IIRC.
> You'd be hard pressed to find any parts with this flaw. And even if you
> should wind up flaming a part (which are astromical odds these days),
6800s
> are still readily available.
>
> --John
>
> -----Original Message-----
> From: cctalk-admin_at_classiccmp.org [mailto:cctalk-admin_at_classiccmp.org]On
> Behalf Of Ben Franchuk
> Sent: Friday, June 07, 2002 02:04
> To: cctalk_at_classiccmp.org
> Subject: Re: [CCTECH] Interesting tidbit on 6502
>
>
> Loboyko Steve wrote:
> >
> > I'm building a 6800 machine right now and I was
> > wondering about this "Halt and Catch on Fire"
> > instruction. Is this for real. This is a serious
> > question. Is there actually an instruction that will
> > overheat the chip?
>
> Not on the 6800 but I believe some FORTH chips have that problem.
> This instruction for the 6800 if remember right just continually
> increments the address bus, ignoring any data read. Only a hard
> RESET will reset the machine from this state. I think the opcode
> is $00.
>
>
>
Received on Fri Jun 07 2002 - 10:00:09 BST