Re: A Commodore 64 Demo Programming Milestone has been reached!

From: Richard Atkinson (
Date: 2001-12-26 18:27:27

On Tue, 25 Dec 2001, eyethian wrote:

> I do have some questions, though. The high resolution FLI mode works fine
> full-screen. It's the multicolor mode that's a problem. It still isn't
> perfected. So, I'm asking a general question here to CBM Hackers emailing
> list. Maybe some VIC-II guru knows.

I'm no VIC-II guru, but I'll present my thoughts here anyway.

> I can force the VIC-II to fetch video matrix data to fill the %01 and %10
> bitpairs in the first three columns of the FLI screen under the SuperCPU.
> But, what about the %11 bitpair? How do I force the VIC-II to fetch colorram
> data to fill this bitpair? From my analysis, the video matrix data that is
> forced onto the first three columns of the FLI screen under the SuperCPU
> will also fill in the %11 bitpair and that is not the intention.

Sounds like you're manually asserting the processor bus using the
SuperCPU. Are you using write accesses, or read accesses from the
appropriate area of video memory so that the DRAM chips assert the bus?

Either way, AEC is always high during these first three cycles (the CPU
half thereof) and so the 4066 analogue switch must always be enabled,
making D11 - D8 the same as D3 - D0.


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