Re: Hardware emulation of 6509 using 6502?

From: Mia Magnusson <mia_at_plea.se>
Date: Mon, 5 Mar 2018 21:51:28 +0100
Message-ID: <20180305215128.000066db@plea.se>
Den Fri, 2 Mar 2018 21:56:29 +0000 skrev smf <smf@null.net>:
> On 02/03/2018 21:48, Michał Pleban wrote:
> >
> > No, it can see only bank 0.
> 
> You can have the video matrix in sram in bank f & the colour ram is 
> always in bank f.

According to the 4256041 schematics, page 15, the enable signal for the
sram, called _VIDMATICS_, is enabled when A15, A14 and A12 are high and
A13, A11 and A10 low, ie $D000-$D3FF

That wouldn't overlap with $0/$1.
 
> You can't do sprites or chargen/bitmap in bank f, it's real nasty.

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.

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Received on 2018-03-05 22:05:39

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