Re: [stella] Games using unofficial opcodes

Subject: Re: [stella] Games using unofficial opcodes
From: "Fred Quimby" <c9r@xxxxxxxxxxx>
Date: Wed, 1 Jun 2005 23:46:17 -0400
I searched some early-mid 80's USENET archives and found that Compute and 
Byte both had such articles.  I couldn't find the actual articles or even 
which issues had them, though.

Also interesting is some apocryphal talk about opcode $12.  I found 
references to this jokingly called "HCF" meaning Hold and Catch Fire.  
Supposedly this opcode was used for chip testing.  The references state that 
this halts the machine, and cycles through all addresses $0-$FFFF and 
repeats infinitely.  But this operation is reportedly very intensive, such 
that if it is run like this for a few hours, the chip will supposedly get 
hot and possibly start to smoke...

Someone with a scope or logic analyzer could easily test this for us.

>From: Gene Johannsen <aofl@xxxxxxxxx>
>Reply-To: stella@xxxxxxxxxxxxxxxxxx
>To: stella@xxxxxxxxxxxxxxxxxx
>Subject: Re: [stella] Games using unofficial opcodes
>Date: Wed, 1 Jun 2005 13:20:53 -0400
>I recall reading an article in Compute! magazine back in the day written by
>somewho experimented with non-std op-codes to determine what they did.  Not
>sure when, who, or what the author might have used as a reference.
>--- Glenn Saunders <mos6507@xxxxxxxxx> wrote:
> > I'd be interested in knowing how early the use of
> > illegal opcodes started and for which platforms.  I
> > vaguely recall that the practice may have originated
> > in the C=64 'scene'.
> >
> > I'm actually surprised that Activision or Imagic never
> > used them.  They might not have known about them.
> >
> > We can use them because we know that (in retrospect)
> > all 2600 systems out there handle them the same way.
> > But back then if they were aware of them, maybe they
> > thought that not all 2600 systems would work right
> > (like the various system changers).
> >
> >
> >
> >
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