CGA Composite Mode under DOSBOX (Commited r3804)

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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby NewRisingSun » 2016-12-14 @ 17:37

I took the liberty of modifying your program to enable the colorburst (portw(0x3D8) = 0x1A0F).
captured.png.raw.zip
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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby reenigne » 2016-12-14 @ 21:45

NewRisingSun wrote:Are you sure you want this with the colorburst disabled?


Whoops, that was indeed an oversight.

NewRisingSun wrote:I took the liberty of modifying your program to enable the colorburst (portw(0x3D8) = 0x1A0F).
captured.png.raw.zip


Thanks - that seems to have worked wonderfully! I was half-expecting the palette register write to take too long and scribble on the leftmost block. This might still be a problem for the PCjr, but if so I can use an IRQ0 for timing.

I'm working on the calibration program now.
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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby basic » 2016-12-23 @ 09:28

NewRisingSun wrote:Patch for PCjr composite support, tested with
  • Ultima II (special PCjr version)
  • B.C.'s Quest for Tires
  • The Seven Cities of Gold

I edited this patch, added instruction in /src/shell/shell.cpp.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby videogamer555 » 2017-6-16 @ 01:40

KiyoteLockeWolf wrote:Since this is a luck of the draw, so to speak, I thought I'd show proof that my utility does do something to give some hope.

Here is a screenshot of Tandy EX Basic, running on a 640x200x2 screen, under composite emulation.

Upon running DOSBOX, I ran my utility, then the BASICA.EXE file.

GWBasic.EXE however, would not take this same method. It shows the composite screen for a second, then switches over to regular CGA with no colorburst.

I only have Dosbox .65 running on my computer right now, because I have bad drivers which crash .63 and .72 on me. I can't test this on other versions of DosBox right now.



Awesomd CGA composite effect! It doesn't work now though at all. It should also be possible to use in text mode. After all, the same glitches you see in a graphics mode, when running composite video, would (on real equipment) also apply in text modes. The reason for this is that in composite video, the color is set by a subcarrier, who's frequency is equivalent to very narrow brightness features (like white text on a black screen). So for this to be true to real hardware, the composite video effect should also work when using 80x25 and 40x25 text modes.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Scali » 2017-6-16 @ 07:03

videogamer555 wrote:Awesomd CGA composite effect! It doesn't work now though at all. It should also be possible to use in text mode. After all, the same glitches you see in a graphics mode, when running composite video, would (on real equipment) also apply in text modes. The reason for this is that in composite video, the color is set by a subcarrier, who's frequency is equivalent to very narrow brightness features (like white text on a black screen). So for this to be true to real hardware, the composite video effect should also work when using 80x25 and 40x25 text modes.


This was superceded by later patches where you can now use the function keys to control composite mode (see the screenshot above, F12 enables or disables composite mode whenever you want).
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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby NewRisingSun » 2017-6-16 @ 11:29

Speaking of which, reengine wanted to update his multiplexer code using my Tandy and Trixter's PCjr captures, six months ago. (I'm not sure whether the latter captures have been made; he has only said that he's bidding on the capture card.)
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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby reenigne » 2017-6-16 @ 11:57

NewRisingSun wrote:Speaking of which, reengine wanted to update his multiplexer code using my Tandy and Trixter's PCjr captures, six months ago. (I'm not sure whether the latter captures have been made; he has only said that he's bidding on the capture card.)


Yes, sorry it's taking me so long. I haven't forgotten, just been busy with other things. I thought it would be easy to modify my calibration code to handle the new captures but doing the easy thing didn't give useful results - it needs a fairly substantial rewrite. Prod me again in a month if I haven't done it by then.
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Re: CGA Composite Mode under DOSBOX (Commited r3804)

Postby MobyGamer » 2017-6-16 @ 17:44

NewRisingSun wrote:Speaking of which, reengine wanted to update his multiplexer code using my Tandy and Trixter's PCjr captures, six months ago. (I'm not sure whether the latter captures have been made; he has only said that he's bidding on the capture card.)


I received the card but took no other action. I'll install it once reenigne completes his rewrite.
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