Path: utzoo!attcan!uunet!fernwood!decwrl!jumbo!ehs
From: ehs@jumbo.dec.com (Ed Satterthwaite)
Newsgroups: comp.sys.atari.8bit
Subject: Re: 6502C vs. 65C02
Summary: they're different
Message-ID: <14219@jumbo.dec.com>
Date: 21 Nov 89 17:47:30 GMT
References: <115200051@uxa.cso.uiuc.edu>
Organization: DEC Systems Research Center, Palo Alto
Lines: 35

In article <115200051@uxa.cso.uiuc.edu>, tle33710@uxa.cso.uiuc.edu writes:

> 	According to the ATARI 130XE Owner's Manual, the Processor in the
> machine is the 6502C Microprocessor, clock speed 1.79 MHz."  Is this the
> same as the 65C02, with more instructions than the 6502, as stated in the
> MAC-65 owner's manual?

No.  The 6502C is a 6502 that is slightly customized electrically to
Atari's specs.  I think the ones I've seen were manufactured by Rockwell.
The customization integrated a little glue logic that was found on the
original 400 and 800.  It's been a while, but I think the clock generation
was changed and tristate buffers for the address lines were integrated.
The 6502C was supposedly used in late 800 production (with a simplified
CPU board) and in subsequent Atari 8-bitters.

The 6502C is instruction-set identical with the 6502 but *not*
pin-compatible.  The 65C02 is pin-compatible with the 6502 (hence not with
the 6502C) but has a number of useful extensions to the instruction set.
I think the 6502C is NMOS; the 65C02 is CMOS.

To add further to the confusion,

 (1) The 6502A and 6502B *are* just 6502s that are guaranteed to run at
     higher clock speeds.  The original 800 used a 6502B, also clocked at
     1.79MHz.

 (2) There are at least two different versions of the 65C02, one identified
     with NCR (or Western Design Center) and one identified with Rockwell;
     the extensions are somewhat different.

Hope this helps.  I have more info in my files at home if anyone really
cares.

Ed Satterthwaite
ehs@src.DEC.COM  /  {...}!decwrl!ehs