Re: Accessing the C64 memory between 65xx chips operations.

From: groepaz_at_gmx.net
Date: Mon, 20 Apr 2020 10:24:32 +0200
Message-ID: <2090705.t9SDvczpPo_at_rakete>
Am Montag, 20. April 2020, 10:17:46 CEST schrieb Gerrit Heitsch:
> On 4/20/20 8:58 AM, Pasi 'A1bert' Ojala wrote:
> > On 20.04.2020 08:56, Gerrit Heitsch wrote:
> >> On 4/20/20 2:29 AM, tokafondo wrote:
> >>> I'd like to know what happens when the VIC gets disabled by software,
> >>> just
> >>> like when the CPU does when loading datassette programs the standard
> >>> way. At
> >>> least, it would refresh DRAM but do the rest of the memory access apply?
> >>
> >> Yes, DRAM Refresh will happen and, as far as I know, VIC will continue
> >> to do DRAM accesses to $3FFF but no longer do badlines.
> >
> > VIC-II will still also perform sprite fetches for each active sprite.
>
> Even while the display is disabled?

yes. you can also trick the VICII into disabling only the badlines, but still
disable the sprites (toggle DEN in similar way you toggle 24/25rows to open
the vertical border)

--

http://hitmen.eu                 http://ar.pokefinder.org
http://vice-emu.sourceforge.net  http://magicdisk.untergrund.net

Knowing what to optimize matters as much as knowing how to optimize.
Otherwise, you'll optimize the wrong thing, and end up with really fast slow
code.
<Michael Abrash>
Received on 2020-05-30 01:33:49

Archive generated by hypermail 2.3.0.