I'm searching over the web for full size of VIC-I, VIC-II, VIC-IIe, VIC-III and VDC screen. I mean real maximal resolution - not only no border 320×200 for VIC-II, but really what is possible - each VIC chip (1, 2, 2E, 3). In case of VIC chips it's more easier than VDC 'cause VDC has variabile resolutions. VDC (no matter of VDC-RAM size) has also limit, but where is? Largest resolution applied is 800×600 by Torsten Kracke, but it's limited by 64K of VDC-RAM. I know there are limits for data flow, but I want to know real maximum no matter of data flow and possible displaying. Why? For example VIC-III has enough RAM for 1280×800 pixels in monochrome mode (1 bitplane) but computer is limited to display 1280×400 in 4 colors only (2 bitplanes). I want to know real maximum of each chip, thank you for understanding.
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On VDC actually 720x700 is the largest resolution done yet. I have done 640x400 non-interlaced which would be 800 lines interlaced but that mode would need too much RAM. Problem with large resolutions horizontally and vertically are more the display-devices which are unable to display them because of their weird timing. As I showed with VDC VGA Mania you can squeeze a 31,5kHz-frequency out of the VDC but must reduce the horizontal resolution to do so.
Post by mrbombermillzy on Feb 3, 2016 22:01:33 GMT
Here are some pictures i took doing some preliminary testing of the vdc. The normal picture is a program I created to test the vdc registers. The screens with the garbage is a resolution stretching test which corrupts the programs display but maxes the screen borders until the sync was lost. Its around the same resolution as tokra describes (720 x 700i) but this is without playing with the sync pulses and character sizes which I believe is the key to getting past the 800 horizontal pixel barrier. Unfortunately the monitor I was using to push the resolution limits (a Commodore badged Aydin Ranger multisync capable of 1024x768i/800x600) gave up and broke! So it may be possible to get higher, but be careful as it could ruin your monitor! With that in mind, im sure the reverse sync ega mode with some tweaking could produce some high res displays on a modern flatscreen.
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800x600 does not change the horizonal sync - it is still at 127 for register 0 = 128 char positions. I only let the display end at position 106 instead of 100 (register 35). You also need to change register 1 to 100 (to display 8*100=800 pixels) and adjust the horizontal sync-position (register 2). Here is the register-setting copied straight out of "VDC Mode Mania 1.1".
It is a good idea to be careful with register 0 updates that go too high. One of my 1901s barely displays PAL-mode (at 15625 Hz) at value 127 for register 0, while the other can go up to 130.
im sure the reverse sync ega mode with some tweaking could produce some high res displays on a modern flatscreen.
Not really. In fact the reverse sync mode is only useful for old EGA-monitors. I was able to display a singal on a modern flatscreen without changing the sync (using the 8563 VDC-chip). VDC VGA Mania does exactly that. For that I have to lower register 0 to 63 (64 char positions) to get a horizontal frequency near the VGA-signal of 31469 Hz. I get to 16000000 / (64 * 8) = 31250 Hz which is close enough for most monitors. However the widest horizontal resolution I could get that way was 400 (50 chars) monochrome or 360 color (45 chars).
Post by mrbombermillzy on Feb 5, 2016 19:30:35 GMT
Im away from my test data atm tokra, but it will be interesting to compare the difference between our register value limits on different monitors. When I mentioned about breaking the 800 pixel barrier I was talking about tweaking the sync pulse rather than changing reg 0 to as high as you can go and maxing out the display start/end registers to get the borders widened to the edge of the screen.
As for ega mode, I was under the impression that it was a better fit for vga output.Perhaps not then.
I will put up some data I took from the ranger monitor and some newer figures that I recorded from my Sony bvm once I get back home.
Its a shame though as the bvm has a max horizontal pixel count of 6/700 so I cant really investigate any more in this department.
Post by mrbombermillzy on Feb 7, 2016 13:14:36 GMT
Ok Im a bit fustrated that I did not write down my detailed observations with the sync width/positioning. I was doing these tests 6 months or more ago, so I cannot remember all the details for that side of things and I wasnt really expecting the monitor to break before I got to finalise and document my conclusions.
Anyhow, the highest resolution that I did manage to record was 832x304/608i on the ranger. This was using the following reg/values:
6/25 2/121 1/104 35/111
I also mucked around with the character sizing as follows (reg/value):
but Im not 100% sure that they helped or were even relevant to the values above.
Ive realized that pushing the max resolution would be very monitor dependant and impractical for early monitors, so Ive decided to look more into extra colour per cell and (due to the monitor killing madness explained elsewhere) Im currently looking into this as a viable enhancement. I will still push the resolution boundaries, but only when using a safe output display like an abundant 15" vga tft panel and when I have time to make an adapter for my rgbi to rgb lead which will interface to the panel using 15 pin din. (Then I would have to punch in the values 'blind' until I hit the low end sync rate that the monitor will accept as 99.9% of vga monitors wont go down to 15-28Khz needed for any custom res between 320 and 600ish h pixels).
I havent really tested hard on the Sony bvm as horizontal pixel count is only 600 or so dots so would be hard to obtain any interesting results.
Ok, I played around a little with my 1084-monitor. The widest I could get was about 832 which was only really stable if I set register 0 to 127. 832 was an edge case on reg 0=126 as was 840 on reg0=127. Either way those values prove no real practical value. I know the 1901-monitor cuts of left and right at about 750 pixels horizontal with no option to squeeze horizontally and the 1084 does not sync well above 600 lines. Most devices can't to either which leaves you at about 720x600 "compatible" resolution. As you mentioned at max resolutions the picture is either horizontally too wide or vertically too tall.
If you manage to get color working beyond 640 pixel width, please let me know. With all my tests the widest resolution for color to work successfully was always at 640 pixel (or maybe 648/656 but not higher).