Re: More CPLD explorations

From: Groepaz <groepaz_at_gmx.net>
Date: Tue, 25 Feb 2014 17:23:13 +0100
Message-Id: <201402251723.14095.groepaz@gmx.net>
On Tuesday 25 February 2014, you wrote:
> On 02/25/2014 03:21 PM, Groepaz wrote:
> > On Tuesday 25 February 2014, you wrote:
> >> On 2/24/2014 10:04 PM, Groepaz wrote:
> >>> On Tuesday 25 February 2014, you wrote:
> >>>> This time, it's PLA replacements.
> >>>> 
> >>>> After fitting, the C64 PLA equations take only a nominal portion of
> >>>> the xc9536(xl) space I stuffed them into.  And, none of the 36
> >>>> registers are used.
> >>>> 
> >>>> I know SuperPLA put a bunch of equations in the unit, for different
> >>>> products, but I was wondering...
> >>>> 
> >>>> Are there any memory mappings that would have been nice to have via
> >>>> the PLA, but are not available?  (external KERNAL at $e000, for
> >>>> instance?) Yes, I understand compatibility and all that.  But, if you
> >>>> had a switchable PLA, what new modes would be of interest? (are there
> >>>> any?)
> >>> 
> >>> maybe one where the VIC does never see chargen (but always RAM
> >>> instead)? that would be very nice for graphic effects :)
> >> 
> >> So, Bank 1/3 doesn't work?  I thought in those banks, charrom is gone...
> > 
> > err yes. thats why i said "the VIC does never see chargen". that
> > obviously means it is always gone, in all banks. that gives additional
> > 8k of memory to use for gfx.
> 
> Of course, you have to make sure that VIC sees the Char-ROM at power on,
> otherwise using the C64 will become complicated.

of course - but such PLA would need to be switchable from 100% original to 
whatever else anyway, else its not very practical for actual use

-- 

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It is essential to understand that everybody sucked in the beginning. 
<Kristofer Dahl>


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Received on 2014-02-25 17:00:41

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