[atari7800] Re: DMA TIMING
- From: Christopher Tumber <christophertumber@xxxxxxxxxx>
- To: atari7800@xxxxxxxxxxxxx
- Date: Tue, 09 Nov 2004 09:39:34 -0500
Eric wrote:
>I just had an AH-HH! moment about this. MARIA has two 800 bit line RAMs, so
>each 160H pixel has 5 bits as a color LUT index. The 320H modes don't
>change how the line RAM is written to, just how it is read. Which,
>unfortunately, means there are only 2.5 bits per 320H pixel, or max 8 colors
>per pixel with one bit shared between the two half pixels.
Any way to get that extra colour back? Since we're limited to 6 colours and
2xbackground in 320B....
Actually, doesn't 320C use 8 colours + background? Except neighbouring bits
must share the same colour. Well, can't have everything, can you...
Actually if you switched between 320B and 320C you'd have 12 colours +
background on screen (without twiddling registers during interrupts). Could be
a hideously complex DL/DLL and might be tough to juggle (maybe with 2
two-scanline vertical resolution for movement so you can alternate 320B/320C?)
Hmmm....
Chris...
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