CGA Composite Mode under DOSBOX (Commited r3804)

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CGA Composite Mode under DOSBOX (Commited r3804)

Postby Jorpho » 2006-6-05 @ 06:02

Moderator note:
See the following post in this thread for info on recent composite CGA enhancements that have been committed to the DOSBox SVN: viewtopic.php?p=284452&highlight=#284452
-- HunterZ



The Mobygames screenshots for Fooblitzky indicate that it can run in CGA Composite mode.

I notice that DOSBox 0.65 gives a little message about supporting Composite CGA if you change the machine type in dosbox.conf from VGA to CGA. However, even when running DOSBox in this mode, Fooblitzky comes up in black and white. The same thing happens in the CVS build.

Do I need to do something else to enable Compositie CGA, or is Fooblitzky doing something not supported by DOSBox?
Last edited by Jorpho on 2012-6-05 @ 16:44, edited 2 times in total.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby mirekluza » 2006-6-05 @ 07:19

The game must support it as well. There must be a switch or a cfg. setting in the game.

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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Qbix » 2006-6-05 @ 09:16

the game probably sets/detects it in a way we don't support yet.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Jorpho » 2006-6-05 @ 13:07

Nothing about a switch in hte manual, it seems.

Is it still common for games to switch/detect Composite CGA in a way that DOSBox doesn't support yet?
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Qbix » 2006-6-05 @ 13:09

well it's not very common, but it is possible. I would have to debug the game to see what it tries to set.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Jorpho » 2007-3-03 @ 21:24

(I realize it's probably not a priority, but FYI this still doesn't seem to have changed in 0.70.)
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Great Hierophant » 2007-3-03 @ 22:32

Fooblitsky doesn't set anything special to enter composite color mode. If you connect it to a composite color monitor, you will see it in color. Othewise you will see it in 4-color CGA (even though the game only uses 2 colors.) DOSBox cannot handle this until it adds a composite CGA selection to the machine types. Actually, in my opinion, there should be a separate listing for monitor type, and support the following devices:

TTL Monochrome (for Hercules and EGA Mode 0Fh)
Composite Monochrome (for all 200 lines modes only)
VGA Monochrome (limited to 8-bit modes)
Composite Color (for all 200 line modes only)
RGB/VGA
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Jorpho » 2007-3-04 @ 00:38

So can anything use Composite CGA mode as it is now?
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Harekiet » 2007-3-04 @ 08:18

If they want to output in composite they have to toggle a certain bit in the cga controller for the color burst. Dosbox detects that and switches to composite mode, seems to work for other composite mode games.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Great Hierophant » 2007-3-04 @ 14:35

There are actually two graphic composite modes, DOSBox only implements the one Harekiet describes, which only works if the game is using a 640x200 resolution. The other composite mode uses the 320x200 resolution and is automatically selected if you the game uses Mode 4, whether the programmer intended it or not. If the game is using the cyan/magenta/white or red/green/brown palettes (and their intense versions), that game will display in color on a composite monitor. If the game uses Mode 5, with its cyan/red/white palette, the game will display in grayscale on a composite color monitor. The only difference in the CGA registers between Mode 4 and Mode 5 is that the color bit is set in the former and clear in the latter.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby abyss » 2007-3-05 @ 11:42

What if you played dos box on a cga composite monitor.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Qbix » 2007-3-05 @ 11:54

doesn't help
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Jorpho » 2008-1-06 @ 02:28

This still doesn't seem to be working...
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Jorpho » 2009-5-14 @ 18:17

This ever get fixed?
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Qbix » 2009-5-14 @ 18:19

perharps. but not for the next version, although that one will have a lot of new machine modes
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby HunterZ » 2009-5-14 @ 19:42

Will any of those machine modes force use of composite CGA emulation regardless of what the game tells the emulated hardware to do?
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby Qbix » 2009-5-14 @ 19:47

nope
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby KiyoteLockeWolf » 2009-5-26 @ 11:48

I might have solved this 4 year old (more?) problem.

I have a very old programming manual. It's been in my posession for years. It is really a xerox of a book, which was stapled together using carpet staples on the end.

From the previous posts, I gathered that setting CGA flags was correct.

On the very first page, (first one before got ripped off), it showed BASICA code to set the active graphics card between Monochrome Adaptor, and a CGA Adaptor in the computer at the same time.

I re-wrote the code in a QBasic wrapper, added my contact info as a 4 second msg, and compiled it into a single EXE. CMPOSITE.EXE

I tinkered with DOSBOX a bit, and it did indeed set the composite mode of the CGA (CGA video mode set of course) emulation.

Will it remain on in between various accesses of programs and other such processes? That depends.

I did a test of a CGA based Turbo Pascal program I wrote to see if the composite setting carried over. It did not. Maybe it's the way my program operates.

But, it did seem to work when running under BASICA at screen 1 & screen 2. (320x200x4) & (640x200x2) which are the composite modes of course.

This is obviously only a temporary fix, but MAYBE, it will work for your game(s).

I would love to see a list of which games this gets the composite flag working again on.

Love to chat about how I did composite CGA video graphics with my Tandy 1000HX, but I'm sure you guys wanna see the program I wrote.



Enjoy! Remember, this is only a homebrew patch that may or may not work.

BTW.. Try at your own risk. It only sets 2 low memory address values, so it won't even hurt a fly as far as I'm concerned.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby wd » 2009-5-26 @ 12:11

Current logic depends on some cga port's bit being set to switch to composite
display, thus you may not "carry over" that mode.
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Re: How do you switch to CGA Composite Mode? (Fooblitzky)

Postby KiyoteLockeWolf » 2009-5-26 @ 12:50

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.
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