Re: More CPLD explorations

From: Gerrit Heitsch <>
Date: Tue, 25 Feb 2014 17:10:13 +0100
Message-ID: <>
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.


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Received on 2014-02-25 17:00:06

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