Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!csd4.milw.wisc.edu!uwmcsd1!marque!studsys!jetzer
From: jetzer@studsys.mu.edu (jetzer)
Newsgroups: comp.sys.apple
Subject: Re: 65C02
Message-ID: <450@studsys.mu.edu>
Date: 1 Mar 89 05:38:58 GMT
References: <8902221021.AA05592@crash.cts.com> <765@microsoft.UUCP>
Organization: Marquette University - Milwaukee, Wisconsin
Lines: 42

In article <765@microsoft.UUCP>, brianw@microsoft.UUCP (Brian Willoughby) writes:
> In article <8902221021.AA05592@crash.cts.com>, delton@pro-carolina.cts.com (System Administrator) writes:
> > What's the shortest way (code size wise) to test for a 65C02 in software
> > (disregarding reading ROM ID bytes since the ROM's and CPU's don't 
> > necessarily go together).  Mainly I need to differentiate between the 6502 and
> > 65C02.  

[lots of gory details deleted]

Here is a routine that someone posted just recently (within a month and a 
half or so).  All I know for sure is that a 65C02 does return a $43, and
a ZIP chip will also return the $43.  I assume it will correctly identify
the other types of processors (I pulled the 6502 out of my unenhanced //e
and put the 'C02 in it after I put my ZIP Chip in my enhanced //e).

Best as I can figure, it load the acc with #0, then tries to do a BRA (a
'C02 opcode, the "80 02") over an RTS.  If you're on a 'C02 or better, it
takes the branch, else it returns.  Then it loads acc with #38, and
tries to perform operation EB on it.  This must be an '816 code, which the
C02 ignores (or treats as a NOP), loads acc with #43, and returns.

(Sorry I can't attribute the code to the original poster.  I was getting
ready to download it [with lotsa other stuff], and I always strip the headers
before transfer to cut down on the xfer time.)


-------------------------------------------------------------------------

This might do the job -- this will return what kind of processor you have,
no matter what your ROMS are like.

300:A9 00 80 02 EA 60 A9 38 EB A9 43 EB 60

The accumulator holds your processor type: $00 for 6502
					   $38 for 65816 or compatible
					   $43 for 65C02

If you like you can add "8D FF 02" to the end of that, and store the
result in 767 where you can say A=peek(767)
-- 
Mike Jetzer
"Hack first, ask questions later."