Jeff Epler's blog

26 May 2005, 0:36 UTC in projects

XY display update


New CRT, new board, same software...

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9 May 2005, 1:58 UTC in software

vgaxy -- create XY scope displays with your VGA card


Software for a virtual terminal and several other toys

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9 May 2005, 1:57 UTC in software

Vector patches for xmame 0.94


With this patch applied, xmame 0.94 does vgaxy-style output for display on an oscilloscope in xy mode

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7 May 2005, 19:32 UTC

More vector game screenshots


I really should mention the website of Jed Margolin which has a lot of information about his time at Atari, including his work with vector games.

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1 May 2005, 20:36 UTC

"Dithered" output increases resolution


By switching between two values in adjacent pixels, the voltage seen at the scope is an intermediate value between the two.] For instance, to display a pixel at X=128.5, alternate between blue=128 and blue=129. This happens because the pixel clock is faster than the bandwidth of the rest of the system---in particular, this signal is at about 75MHz, while the scope has a "20MHz bandwidth limit" button.

So without complicated extra hardware, I've got a nice 512x512 output, which gives me a 64x48 character vector terminal. It's a lot more readable than this screenshot makes it appear. 768x768 (a 3-pixel ordered dither @ 50MHz) and 1024x1024 (4-pixel, 37MHz) dithered resolutions may also work. Watch this space.

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1 May 2005, 18:16 UTC

MAME vector display on the oscilloscope


Yep, it works. Too bad about the low resolution. More game pictures below the fold.

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29 April 2005, 1:04 UTC

Working Z-axis


With a simple transistor, the Z axis works pretty well. The linearity is better now that I'm using some 10b2 tees and terminators (50 ohms) on the X and Y inputs, too.

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17 April 2005, 15:47 UTC

Vector "text" display


Displaying a message, even.

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17 April 2005, 2:33 UTC

Animated XY display

16 April 2005, 16:53 UTC

VGA to 'scope display

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