Re: DRAM refresh

From: Segher Boessenkool <>
Date: Sat, 15 Oct 2016 15:54:26 -0500
Message-ID: <>
On Sat, Oct 15, 2016 at 09:05:11PM +0200, wrote:
> Borders were still "easy enough" to guess along the lines: VIC turns on the border when it reaches the end of the 25th row. It doesn't turn it on when passing through the end of 24th. But if I switch it to 24 rows right after the 24th is already rendered, then it may "think" that the border is already on and skip turning it once more.

More exactly, it turns off the border in raster line 0f7 (hex) if RSEL=0
and in raster line 0fb (hex) if RSEL=1 (these are PAL timing, from 8565).

The video matrix (and the memory fetches associated with it) is independent
of the borders and its timing.  Which of course you found out later :-)

(Fetches ("badlines") are done whenever the raster (the Y coordinate) is
in [030,0f7) and the low three bits are equal to YSC, the low three bits
of reg 11).

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Received on 2016-10-15 21:00:02

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