Re: 6502 illegal opcodes questions

[pausch@saaf.se (Paul Schlyter)]

In article <1149383070.763983.291190@h76g2000cwa.googlegroups.com>,
mdj <mdj.mdj@gmail.com> wrote:

> Paul Schlyter wrote:
> 
>> I fully agree with that!  The API is the specification, not the
>> implementation.  There might be some parts of the library which
>> can be called by outside code but wasn't intended to be called in
>> that way - they're not part of the API, even though they're part of
>> the library!
> 
> Of course, if you use features of a library that aren't part of it's
> documented interface you'll eventually be cursed by almost everybody.
> 
> Hey, we're almost back on topic, considering this was supposed to be
> about 'undocumented opcodes' :-) Of course, my feelings on using
> undocumented library calls is much the same as my feelings on
> undocumented opcodes. They are very similar problems.
> 
> Matt

In the Apple II world we had other similar situations: calling Monitor
ROM routines at some fixed address.  Or calling routines in the Applesoft
Basic ROM's.

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