Re: writing to cart port (not IO space) on 64

From: Jim Brain <*brain_at_jbrain.com*> Date: Sun, 26 Feb 2017 00:11:49 -0600 Message-ID: <2b479461-b8f8-c31e-d857-fb634b8ae3e2@jbrain.com> · brain_at_jbrain.com

On 2/25/2017 12:08 PM, Daniel Kahlin wrote:
>
>
> On Fri, 24 Feb 2017, Jim Brain wrote:
>
>>> ; optional to avoid visible glitches, wait until border area
>>>         ldx     #$30
>>> lp:
>>>         cpx     $d012
>>>         bcc     lp
>> OK, I partially understand this.  Is it because color ROM is no 
>> longer wired to anything?  Because, I assume you could relo the 
>> screen RAM to somewhere in the first 4kB
>
> It's because the character ROM is not visible to the VIC-II in ultimax 
> mode.
>
> I suppose you could put the charset in RAM and have full speed writing 
> with the screen visible.
>
> /Daniel
>
>
>       Message was sent through the cbm-hackers mailing list

OK, understood.  So, why does AR and EF have RAM in the IO space?  Is it 
because RAM is so limited when in Ultimax mode?

Jim

-- 
Jim Brain
brain@jbrain.com
www.jbrain.com

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