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Post by bjonte on Feb 11, 2020 20:16:03 GMT
Congratulations oziphantom!
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Post by tokra on Feb 11, 2020 20:20:25 GMT
Had to check out XLACE132 first. Trying to analyze what it does, I think it sets up a 4 pixel-wide font that is then put out with 4 pixels interspacing in 66 columns. Then it waits for vertical retrace, moves the image 4 pixels to the right, point to another video- and attribute-RAM and displays the next-half picture. Then after vertical retrace back to step 1. This would also explain the colour-bleed of reverse and underline. Maybe Strobe can explain a little more? I thought about doing something similar for a 40-column-mode for the VIC-20, but Aleksi Eeben independently of me had the same idea and went through with it: sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=2&t=8529&p=96426
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Post by strobe on Feb 11, 2020 22:49:34 GMT
Had to check out XLACE132 first. Trying to analyze what it does, I think it sets up a 4 pixel-wide font that is then put out with 4 pixels interspacing in 66 columns. Then it waits for vertical retrace, moves the image 4 pixels to the right, point to another video- and attribute-RAM and displays the next-half picture. Then after vertical retrace back to step 1. This would also explain the colour-bleed of reverse and underline. Maybe Strobe can explain a little more? I thought about doing something similar for a 40-column-mode for the VIC-20, but Aleksi Eeben independently of me had the same idea and went through with it: sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=2&t=8529&p=96426Very close Tokra! It's actually 5 pixels wide font with 5 pixel gap - 3 blank pixels in the font & 2 inter-character gap pixels - so 10 pixels wide x 66 = 660pixels wide, so not much wider than 80 columns. You can see the full 5 pixels used in WwMm# etc. which causes a little character clumping but looked better overall. Smooth scroll is used to shift the screen 5 pixels each frame. The char & attribute ram pointers are toggled 66 bytes each frame. Reg #27 is set to 66 to skip over the other half of the char row every line. This way each character row in memory is a 132 byte chunk and you can just write multiple lines non-stop which is how the screen set up is drawn. I considered completely separate screen/attribute areas for each frame which is conceptually simpler but not as easy to use in practise. This could be done with a 4 pixel wide font for 160 columns, but I thought that was going too far Didn't know about the VIC-20 one, thanks for the link but doesn't surprise me this has been done on other platforms. The same technique could be used on the c64 for 80 columns in text mode. Cheers, Strobe * for visual neatness it's actually 67 / 134 to have a blank column so smooth scroll is less ugly.
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Post by Pyrofer on Feb 12, 2020 22:48:12 GMT
The Prize has been posted out! I might do this again next year, but I hope the entries here inspire people to do more with the VDC. I am still working on my demo, fighting VDC hardware bugs and VICE Fingers crossed I will be able to present that sometime soon... If I ever get a sid to play in native 128 mode.
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