Re: Hardware emulation of 6509 using 6502?

From: smf <smf_at_null.net>
Date: Tue, 6 Mar 2018 23:28:07 +0000
Message-ID: <7285807a-8adc-cc72-8b2b-b144de50c313@null.net>
On 05/03/2018 20:51, Mia Magnusson wrote:
>
> Well, the limit is that you can only access 1k in bank F, but there
> seems to be no special limit on the usage of that 1k. Usually it's
> probably best to use it for screen ram but in theory you could store
> sprite data there instead, or whatever you want to have there.

My understanding is that:

vicdotsel contols whether font & sprite fetches come from the character 
rom or dram bank 0, these fetches cannot come from static ram.

statvid selects whether the video matix comes from static ram or dram 
bank 0, when fetching from static ram it ignores the vic2 bank and the 
screen address & you are locked into that 1k page.

The motherboard has complicated logic to coordinate this.



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Received on 2018-03-07 01:00:38

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