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From: po87553@korppi.tut.fi (Pasi 'Albert' Ojala)
Newsgroups: comp.sys.cbm
Subject: Re: Undocumented 6502/6510/8502 instructions?
Message-ID: <1990Nov17.211343.17356@funet.fi>
Date: 17 Nov 90 21:13:43 GMT
References: <4125.27440883@cc.nu.oz.au> <1990Nov16.214729.27679@Neon.Stanford.EDU> <1990Nov17.163800.12713@funet.fi> <1990Nov17.185259.10564@evax.arl.utexas.edu>
Sender: news@funet.fi (#News )
Reply-To: po87553@korppi.tut.fi (Pasi 'Albert' Ojala)
Organization: Tampere University of Technology, Finland
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In article <1990Nov17.185259.10564@evax.arl.utexas.edu> cs4344af@evax.arl.utexas.edu (Fuzzy Fox) writes:
>The 6502, 6510, and 8502 are all internally the same as far as
>instruction processing goes, so the illegal opcodes generate the same
>effects on all three CPU's.  The reason that many games crashed on the
>128 is that they would often accidentally twiddle some memory locations
>that differ between the 64 and 128 (such as $D030, which does nothing on
>the C64 and can switch to 2 MHz-no-video mode on the C128).
>..

I will surely disagree. The real reason for crashing was the fact that
undocumented commands did't work on 8502 at all. At least all these so
called undocumented op-codes were 'accidents' produced by the other
commands and the processor design. I am sure that both 6502 and 8502
differ significantly in their inner design.

Most of the commands were JAM-operations anyway ($02 etc.)..

An if I am wrong... this is what I believe in..

Pasi Ojala, Sysop Of Pasbox

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