On Fri, Jan 22, 2016 at 03:19:11PM +0000, Steve Gray wrote: >Hmm, I wonder if a singe line of 64 LEDs would work better... one for >each K The 4 by 16 display was wired as 8 by 8, if I remember correctly, so it used two 3-to-8 decoders for driving the rows and columns. Likewise, my 8 by 32 display was wired as 16 by 16 (two adjacent physical columns were one logical column). The solder side of the board looked pretty funny. Too bad I did not take a picture before I gave it to Ruud. I would say that a matrix layout is definitely easier than a linear layout. With a matrix, you can easily tell if something happens at $7fxx or at $80xx, for example, because it would be a completely different row (or column), even though it is an adjacent column (or row). >then maybe you could add a small capacitor to each LED to make them >stay on a little longer? That will mean more decoder chips but might >give a better result. Like I wrote, I think that modern super-bright LEDs are simpler. And the capacitor would ruin the reliability of the instrument, if you wanted to use it for debugging or profiling. BTW, back then, Andreas Boose wrote some clever code generator that would show a "Knight Rider" pattern on his display. :) The trick was that you had to JMP around in the memory, to avoid stray memory accesses that would ruin the display. No stack (no subroutines, no interrupts), no writes to RAM while it is running. Just use the registers. Marko Message was sent through the cbm-hackers mailing listReceived on 2016-01-22 16:02:10
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