>6800 from long ago had a  nice one -
>We called it   HCF
>aka "Halt & Catch Fire" :-)

        Don't tell me that! ;oD Yesterday I was fixing a pinball machine (Jurassic=
 Park - Data East Co.) and looking at the CPU board I though=
 "hmmm...6502...too crazy to use it in a pinball..." and when I turned my=
 vision to one of the 6821 PIA (there are LOTS of them in the board) I saw=
 something interesting - The chip MELTED and throw some brown guts in the=
 board. Like a crocroach (again, where is my english dictionary?) when you=
 step on it. Very nice indeed. Lots of repair and board rework time... :o\

>When implemented the cpu turned into a binary hardware counter with
>addresses appearing on address bus at clockspeed.

        An expensive 4040? :o)

>An excellent instruction for testing address decoders etc and a good trap=
 if
>the cpu ran away ever. When it did it would often as not strike a HCF and
>the system would lock in this interesting mode.

        Ah, so it is "Halt and Count Forever" :o)

>Presumably it was intended as  a hardware test.

        Or a cheap way to turn your $300 microprocessor into a $5 binary counter?=
 :o)


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Alexandre Souza
taito@terra.com.br
http://planeta.terra.com.br/lazer/pinball/

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