Re: R65C02 PI

[johnlb@primenet.com (John Bowling)]

In article <4vv3gg$an7@europa.frii.com>,
Randy Shackelford <shack@deimos.frii.com> wrote:
>In article <322252E2.678C@cup.hp.com>, Michael Mahon  <mahon@cup.hp.com> wrote:
>>John Bowling wrote:
>
>>I was never a big game fan, so there may be a lot of stuff out there
>>that uses undocumented opcodes, but I sure haven't seen it!
>>
>>The one trick I _have_ seen is the JSR-to-last-byte-of-page, but
>>that 6502 bug was fixed in the 65C02, so //c's and enhanced //e's
>>wouldn't be able to run even _those_ programs!
>
>I think you mean JMP indirect, it's the one whose operand can't cross a 
>page boundary on a 6502.
>
>>Since there has been little outcry about //c and //e game compatibility,
>>I conclude that undocumented opcodes are not a major issue.
>>
>>Does anyone have a list of programs that are so affected?
>
>All the old games which I have tried with the exception of One on One work
>on a //c and IIgs for that matter.

Europe Ablaze, Think Tank, and Evelyn Wood Speed Reading don't work on the
gs.  I haven't bothered to look into why, but it has to be related to
either use of jumps into RAM or Dos/ProDOS which are undocumented, or use
of 6502 undocumented opcodes.

Think Tank is the only really usefull one, and I'ld love to have a gs
version of their current iteration on the Mac (More), but they never did
any version for the gs, just that hack job of a // version.

John

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