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Post by Pyrofer on Mar 17, 2017 11:36:37 GMT
This sounds like it is going to be my go-to test bed when developing for the 128. The poor VDC emulation has really hampered my testing using VICE. If all of Tokra's stuff runs then my stuff should
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Post by Pyrofer on Mar 12, 2017 14:11:53 GMT
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Post by Pyrofer on Mar 10, 2017 12:03:20 GMT
The colours on my one were based on a mathematical distribution of the colour space rather than trying to achieve how a CRT "looked" to the human eye.
I know John Carlsen spent a lot of time measuring internal voltages and balancing all his values to achieve a very specific balance of colours for a particular CGA compatible monitor.
I have no idea how much variance there was within CRT monitors which is why I just based mine how how we thought the colours "should" be divided. It might be that there is an official reference for the original IBM CGA spec that monitors had to conform to?
This is the formula mine is based on from the wiki entry for CGA
red := 2/3×(colorNumber & 4)/4 + 1/3×(colorNumber & 8)/8 green := 2/3×(colorNumber & 2)/2 + 1/3×(colorNumber & 8)/8 blue := 2/3×(colorNumber & 1)/1 + 1/3×(colorNumber & 8)/8
This was then applied to get the correct voltages out of my DAC for the analogue RGB. As far as I can see this is the only reference for how the colours should look and any variance would be on a per monitor basis.
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Post by Pyrofer on Mar 10, 2017 8:19:40 GMT
Hey, I didn't say "Mine is the best" I said it was the best I have seen I really wanted to compare the output but sadly those photos just don't show for me. It's true that they all mostly work the same way but there are some facts that greatly change the quality of output. A logic based solution is better than a passive based one. Trying to get the intensity bodged in with resistors and diodes/transistors is never going to look as good as doing it all in logic then using a DAC to get the output. Any logic based solution is going to be judged on the speed of the logic chips used. Not only is absolute speed important (if they don't switch fast enough you get poor edges on the colours) but having the gates switch at the same speed is critical too. There are more gates involved in the brown colour than just r/g/b etc. This can lead to artifacts on the edges of certain colours. So there is a whole wide scope of variation in adapter. When I started making mine it was pretty much the only design other than the basic resistor circuit out there... I did it to encourage more use of the VDC and 80 columns. I think I achieved my goal, it's great to see other people working on it and more people using the 80 column chip. Even if it is a little bit late.
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Post by Pyrofer on Mar 9, 2017 12:23:03 GMT
You are aware of my adapter are you?
I use a programmable logic device to turn RGBi into RRGGBB with the brown fix done digitally inside the logic. I then use a 6bit DAC to convert the new RRGGBB to RGB Analogue.
So far, I have not seen any adapter that comes close to the quality of the output from mine and sadly your photos are not showing so I can't compare. I do get from your text though that you have only done the digital to analogue part of the circuit (same as me) with no scanrate conversion. I designed mine to work directly with the Gonbes by having a 15pin VGA style connector for it's output which connects directly with a common cable to the gonbes for VGA upscaling.
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Post by Pyrofer on Mar 3, 2017 19:34:44 GMT
I read that as "write 128 disks" being "create floppies from .d64 images rather than move individual files.
I guess we need clarification.
Do you simply want to move files around or actually transfer whole Commodore disk images onto floppies?
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Post by Pyrofer on Mar 3, 2017 17:43:28 GMT
No way. You are better off getting a modern PC driver interface like the XU1541 or a zoomfloppy and using a real 1541 etc to write the disks.
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Post by Pyrofer on Feb 15, 2017 11:17:54 GMT
I will definitely be following this with interest. If it becomes a valid way of testing my code instead of copying onto real hardware it could save me a lot of time.
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Post by Pyrofer on Feb 14, 2017 12:46:23 GMT
It will be fun to try my code against it and see how it copes with the smooth scrolling 80col bitmap and VGA mode etc.
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Post by Pyrofer on Feb 7, 2017 9:12:02 GMT
Thanks for that I shall stop hijacking this thread now...
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