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(a)wxs.nl>
To: <cctalk(a)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(a)p850ug1.demon.co.uk>
To: <cctalk(a)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