Re: 6502 illegal opcodes questions

["John B. Matthews" <nospam@nospam.com>]

In article <e5c1e4$24tu$1@merope.saaf.se>,
 pausch@saaf.se (Paul Schlyter) wrote:

> In article 
> <nospam-7B7751.02054028052006@network-065-024-007-028.columbus.rr.com>,
> 
> > 222222In article <e598gn$134q$1@merope.saaf.se>,
> >  pausch@saaf.se (Paul Schlyter) wrote:
> > 
> >> In article 
> >> <nospam-467DFC.23375126052006@network-065-024-007-027.columbus.rr.com>,
> >> 
> >>> In article <e56rj1$7lo$1@merope.saaf.se>,
> >>>  pausch@saaf.se (Paul Schlyter) wrote:
> >>> 
> >>>> In article <1148544621.115246.248890@y43g2000cwc.googlegroups.com>,
> >>>> mdj <mdj.mdj@gmail.com> wrote:
> >>> [...]
> >>>>> The key concepts that are missing here are pointers, and more 
> >>>>> specifically,
> >>>>> the ability to perform arbitrary arithmetic on pointer types.
> >>>> 
> >>>> FORTRAN, Pascal and Ada lacks this too.
> >>> [...]
> >>> 
> >>> This is certainly false for Ada:
> >>> 
> >>> http://www.adapower.com/rm95.php
> >>> 
> >>> In particular, the standard package Interfaces.C.Pointers overloads the 
> >>> "+" and "-" operators for just this purpose.
> >>> 
> >>> http://www.adapower.com/rm95/RM-B-3-2.html
> >> 
> >> OK, Ada has pointer arithmetic - but is it arbitrary?
> > 
> > Well, it's arbitrary up to the limit of erroneous:  you can't access
> > memory that's forbidden by the OS:-)
> 
> Ouch .... so much for the "security" of Ada......

I don't see how this follows. One of the goals of Ada is to find more 
errors at compile-time, leaving fewer for run-time. It is certainly 
possible to write an erroneous program in Ada, but one must do so 
explicitly. It's much harder to do by accident.

[...]

-- 
John Matthews
jmatthews at wright dot edu
www dot wright dot edu/~john.matthews/