Re: BASIC and System ROM replacements

From: Jim Brain <>
Date: Fri, 24 May 2013 16:16:23 -0500
Message-ID: <>
On 5/24/2013 4:08 PM, Spiro Trikaliotis wrote:
> * On Fri, May 24, 2013 at 11:35:17AM -0700 Steve Gray wrote:
>>     That reminds me of something I read about the C64GS kernel actually having
>>     windowing routines built in. Has anyone disassembled the kernel to verify
>>     it?
> I do not have the disassembly here ATM (problem with the access to the
> machine), but IIRC, the 64GS has a stripped-down version of the kernel.
> That is, no fancy windowing routines.
> Regards
> Spiro
>         Message was sent through the cbm-hackers mailing list
Not to take this too far off topic, but I would be interested in an idea 
that would allow the ROM areas to be "banked" in such a way that you 
could fit 16kB of KERNAL or BASIC into a 8kB space.  I know the trivial 
is to use a "secret" location, but that's too simplistic.  I was 
thinking of something where a sequence of address accesses would trip 
the bank, and then if there was an IRQ when in the wrong bank, any 
access to the normal locations would "trip" it back by writing to a 
single location.  That way, accesses to ROM routines would incur no more 
than a few cycles to flip back to the correct bank.

But, that was just the initial idea.  If a solution could be found, that 
would open up lots of expansion ideas (You could offer many banks of 
stuff) within a single ROM window.


Jim Brain

       Message was sent through the cbm-hackers mailing list
Received on 2013-05-24 22:00:50

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