You may be confused about this. I don't know of a single NMOS 6502 that
didn't adhere to the MOS-technology instruction set. There's no telling
whether that included the undocumented opcodes, but since Synertek and
Rockwell used the MOS mask set, I suspect there was no difference. The later
Synertek parts may have been different since they shrank the die and got a bit
more speed, offering a 4 MHz 6502-C, which was an NMOS part and worked
perfectly in NMOS-targeted systems that didn't work with the later CMOS parts.
Dick
----- Original Message -----
From: "Sipke de Wal" <sipke_at_wxs.nl>
To: <cctalk_at_classiccmp.org>
Sent: Friday, June 07, 2002 12:34 PM
Subject: Re: [CCTECH] Interesting tidbit on 6502
> Problem with the 6502 is that different versions
> from different manufacturers had different
> undocumented instructions. So for the general
> public this was not much of a boon ....
>
> The Z80 situation was much better
>
> Also the 65C02 (the special CMOS version)
> als was more reliable in this respect
>
> Sipke de Wal
> -----------------------------------------
> http://xgistor.ath.cx
> -----------------------------------------
>
>
> ----- Original Message -----
> From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
> To: <cctalk_at_classiccmp.org>
> Sent: Friday, June 07, 2002 8:03 PM
> Subject: Re: [CCTECH] Interesting tidbit on 6502
>
>
> <snip>
> >
> > Many processors (and other chips for
> > that matter) have undocumented
> > instructions used for factory testing.
> >
> >
> > -tony
> >
>
Received on Fri Jun 07 2002 - 14:05:09 BST