Re: 6502 illegal opcodes questions

["Sam Gillett" <samgillettnospam@diespammermsn.com>]

"Paul Schlyter" wrote ...

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

Programmers in the Commodore world also made extensive use of calling ROM
routines.  But, not all of them were undocumented.  Commodore listed the
entry address for many of the more useful Kernal routines, along with a name
for the routine and a brief description of its function, in the C64
Programmer's Reference Guide.

When the C128 came along, Commodore also documented Kernal calls for that
machine in the C128 PRG.
-- 
Best regards,

Sam Gillett

Change is inevitable,
except from vending machines!