Re: KERNAL cartridge

From: David Wood <>
Date: Thu, 18 Nov 2010 23:02:11 -0600 (CST)
Message-ID: <>

Considering the purpose of this cart is to eliminate the need to desolder a
kernal rom, would you be against using a clip to the 6510's PIO pin to
en/disable your ultimax trigger depending on the port pin?  This would only
be one lead to run into the system.

I can't think of a good way of doing this from outside the c64, but I'd love
to hear others' input. :)


On Thu, 18 Nov 2010, Jim Brain wrote:

> Given the fact that many C64 machines have non socketed KERNAL ROMs, I
> continually receive requests for a KERNAL ROM cart.
> Academically, I see how to do it by driving ULTIMAX mode during
> $e000-$ffff reads, but that only works when RAM is banked out.  Does
> anyone have an ideas on how to accomplish that?
> I know I could implement a mirror for $0 and $1, but folks say those
> addresses and the R/W signal don't show on the external bus.
> Implementing a complete 6510 on the cart to mirror the internal 6510
> might work (discarding write operations), but that's truly a brute force
> approach and hardly seems worth the effort.
> Jim
> --
> Jim Brain, Brain Innovations                                      (X)
> Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
> Home:
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Received on 2010-11-19 06:00:15

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