Re: $D012 values on C64

From: Groepaz <>
Date: Tue, 18 Jun 2013 18:37:39 +0200
Message-Id: <>
On Tuesday 18 June 2013, you wrote:
> Hello!
> I am writing the software for my MultiKernal Flash device for C64. I
> found that during writing to the Flash chip I need to disable chip
> reads, because otherwise they mess up with magic write sequences.
> But then VIC-II cannot read character ROM, which results in garbled
> screen display. Therefore I would like to write to the Flash chip only
> when character ROM is not needed - i.e. when the lower or upper border
> is drawn. For this, I need to consult the $D012 register.
> However, I have only a PAL machine and I don't know how the values look
> like on a NTSC machine. I would assume that they both start at 0 and the
> border starts/ends at the same positions as with PAL, only possibly the
> total number of lines is different - is that a correct assumption?

lines $30 - $f8 are the screen area, rest is border. no difference between 
pal/ntsc there. (i would try to avoid checking for any rasterlines > $ff and = 
$00 - its a bit tricky to get it working right on both pal/ntsc under all 


Da singen sie: We are red, we are white, we are Danish Dynamite - Wir sind 
rote, wir sind weiße wir sind dänische..., äh... 
<Heribert Faßbender>

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Received on 2013-06-18 17:01:19

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