Subject: Re: [stella] 12 chars/line!? (was: re: optimizations; Call forsuggestions) From: Piero Cavina <p.cavina@xxxxxxxxxxxxx> Date: Thu, 25 Sep 1997 22:05:22 +0100 |
At 10:48 -0700 24-09-1997, Greg Troutman wrote: >> That would allow 48/4=12 charachters per line (without flicker)! >> >> Can it be done? > >You mean a half-width font, instead of hard-coded graphics? Sure. Very >problematic though. There is not enough time within the six-digit trick >to read and combine the 4 bit parts into one graphics register. So, it >has to be done in RAM beforehand, and that means 30 bytes for one 5 >scanline high line of text. Yes, it's exactly what I was thinking. >You can't very easily re-use that RAM area >for drawing multiple lines of text in the same frame, because the loop >that would combine 12 4-bit characters into 6 one byte graphics data, >five scanlines high, would take well over a thousand cycles, I think, >producing as many as 20 blank scanlines while you busily reload that RAM >area... Are you sure it would take so much time? The font could be stored in this way...: ; letter "A" byte %01000100 %10101010 %11101110 %10101010 %10101010 ie - the same 4-bit character twice in 1 byte, so that combining two of them into 1 byte can be done without shifting bits... P. -- Archives updated once/day at http://www.biglist.com/lists/stella/archives/ Unsubscribing and other info at http://www.biglist.com/lists/stella/stella.html
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