Re: Ribbon Cable

From: Gerrit Heitsch <>
Date: Wed, 18 Dec 2013 15:53:41 +0100
Message-ID: <>
On 12/18/2013 03:22 PM, wrote:
> On 2013-12-18, at 01:56, Gerrit Heitsch <> wrote:
>>> Using the MMU backwards to check for ROM at $e000 and then switching to
>>> Ultimax mode on access to present the KERNAL is a significant hack I think.
>> Yes, but for that you have to do things that are outside the normal C64 timings. You have to make a lot of assumptions on parts speed and do multiple things within a clock cycle.
> Right, but is there a more (not only politically but practically) “correct” way of doing this?

If the expansion port doesn't carry the signals to do it cleanly (like a 
'only disable internal ROM' or the trick Sinclair used), then you can't 
do it, simple as that.

Everything else makes assumptions that might or might not be true on all 
systems (see SX64 problems) and in my book that's not a clean design.


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Received on 2013-12-18 15:02:53

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