Re: Apple IIe + ProDOS = Headache

[dempson@actrix.gen.nz (David Empson)]

Paul Schlyter <pausch@saaf.se> wrote:

> In article <20040625200651094+1200@News.Individual.NET>,
> Roger Johnstone  <rojaws@orcon.net.nz> wrote:
>  
> > ProDOS technical note #23 says:
> > 
> >   ProDOS 8 1.3
> > 
> >   Warning: This is not a stable version of ProDOS due to an
> >   illegal 65C02 instruction which was added. This version can
> >   damage disks if used with a 6502 processor.
> > 
> > http://web.pdx.edu/~heiss/technotes/pdos/tn.pdos.23.html
> > 
> > I take it to mean that it was a valid 65C02 but invalid 6502 instruction,
>  
> The text said "illegal 65C02 instruction".  And since the 65C02 was
> backwards compatible with the 6502 at the machine code level, it was
> definitely an illegal 6502 operation as well.

The technical note was badly worded.  They didn't use an "illegal 65C02
instruction".  It should have said that they "illegally used a 65C02
instruction".

-- 
David Empson
dempson@actrix.gen.nz