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From: liang@cvl.UUCP (Eli Liang)
Newsgroups: net.micro.apple
Subject: Re: Re: Undocumented 6502 Opcodes
Message-ID: <139@cvl.UUCP>
Date: Wed, 6-Mar-85 18:40:22 EST
Article-I.D.: cvl.139
Posted: Wed Mar  6 18:40:22 1985
Date-Received: Sat, 9-Mar-85 19:58:55 EST
References: <9@zurton.UUCP> <381@utai.UUCP>
Organization: Computer Vision Lab, U. of Maryland, College Park
Lines: 23

> I tried to execute some of the unused 6502 opcodes and found one that
> seems to conform to the described HCF specs.  That is, the processor 
> seems to hang up and doesn't go anywhere until it gets a reset.
>    Of course, I didn't let it sit there long enough to find out
> if the processor would self-destruct.  If anybody is willing to
> satisfy our curiosities, the op-code was $12.  As noted, the presence
> of the HCF instruction may depend on the chip manufacturer.  Unfortunately,
> I forgot to check who made mine.
>    Greg Dudek

This is the exact instruction which I mentioned in my previous article.
$12.  I think that there must be some truth in the HCF instruction for the
6502.

-eli

-- 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Eli Liang  ---
        University of Maryland Computer Vision Lab, (301) 454-4526
        ARPA: liang@cvl, liang@lemuria, eli@mit-mc, eli@mit-prep
        CSNET: liang@cvl  UUCP: {seismo,allegra,brl-bmd}!umcp-cs!cvl!liang