Re: C64 GS

From: Marko Mäkelä <>
Date: Tue, 30 Dec 2014 09:35:56 +0200
Message-ID: <20141230073556.GA1536@x60s>
On Tue, Dec 30, 2014 at 06:47:11AM +0000, Baltissen, GJPAA (Ruud) wrote:
>Of course I want to include the C64 GS disassembly into the one I 
>already have. I did a difference check and then I found this huge 
>difference at $F72C of over 1000 bytes! My first thought that I was 
>using the wrong file but then my findings were confirmed by the 
>comments at Bo's site.

It was probably me who wrote those comments.

>- Why this huge difference? I mean, if the GS was meant to be a 
>stripped down C64 then IMHO it would have been sufficient to change 
>some branches.

There was no keyboard on the 64GS. I would believe that Commodore wanted 
it to be like the UltiMax, only to be used with cartridges. You (or 
Patryk) got an empty 64GS case from me. IIRC the user port, tape port 
and the serial port were hidden by the case. So, that hardware was not 
supposed to be used by any cartridge software. It would make some sense 
to block all access to these peripherals in the KERNAL.

Back in the day, I read in some magazine that the 64GS would display an 
animation that you should turn off the computer and insert a cartridge.  
I do not remember seeing any evidence of this in the ROM that I 

Still, I am a bit puzzled about Commodore's decisions. If they got lots 
of C64 circuit boards that they wanted to get rid of, by turning them 
into game consoles, why did they design a new ROM for it? Why not just 
use the boards as is?

When it comes to the discussion on how to mark up different firmware 
versions, I think that the preferred way is to do it via branches in a 
version control system (such as Subversion or git). For my C2N232 
firmware, I initially did version control by a compile-time constant, 
and it got messy as soon as there was some refactoring of the code.


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Received on 2014-12-30 08:00:03

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