Re: 8502 vs 6510 undoc. opcodes

From: Jim Brain <brain_at_jbrain.com>
Date: Thu, 12 Oct 2023 16:56:33 -0500
Message-ID: <a2414887-a0c0-46bc-86bd-289770c772f0_at_jbrain.com>
On 10/12/2023 4:41 PM, silverdr_at_srebrnysen.com wrote:
>>> On Thu, Oct 12, 2023 at 3:44 PM <silverdr_at_srebrnysen.com> wrote:
>>> Are 8502 undocumented opcodes generally compatible with 6510 ones?
>> On 12 Oct 2023, at 21:03, Craig Taylor <ctalkobt_at_gmail.com> wrote:
>>
>> For the most part, I believe so - however when doing the C= Hacking Undocumented opcodes I was originally on a 128 - and that may have introduced some of the issues that were reported about the table I created (that, and potentially interpretation - "one of these days" I'd like to do it w/ UTF8 w/o having to resort to psuedo logic symbols).
> I see. The reason I ask is that I always thought that C128 compatibility with C64 (and that unfortunately has to include undocumented opcodes) was on the 99-ish percentage level but got hit with an "undocumented don't run as expected" argument. As I don't know much about the 8502, I assumed it's still an HMOS-II, similar to 8500 so it should behave, shouldn't it?

I'd be interested in more info on this claim.  I was always under the 
impression the lack of hiding the VIC-IIe extra registers was the culprit.

Jim

-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2023-10-13 02:00:04

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