Linux + J-Pac + 15Khz screen without ArcadeVGA ?

[AMIGrAve]

Hi,

I just bought a Pit Fighter with a 15Khz screen inside.
I would like to use Linux for this mame station project.
I've got a nVidia Riva TNT2 and a Matrox Millenium G200.
I've generated a modeline with http://xtiming.sourceforge.net/cgi-bin/xtiming.pl
and the specifications I read at http://www.klov.com/monitor.html.

The modeline is :
Modeline "368x248@60" 7.16 368 400 424 456 248 253 256 261

Actually, I just wan't to make some tests, so I fired up knoppix, i added the modeline and tried to start X.
X won't start claiming that the pclock is too low for that gfx card. The MGA and the NVIDIA modules (i tried both cards) print in /var/log/Xfree86.0.log   -->  Clock range:  12.00 to 350.00 MHz , but it prints that for all my cards, even for my Nvidia Geforce 2 mx in another computer.
If X think that the lowest pclock frequency for these cards is 12.0 then I understand that it refuses this modlines wich uses a 7.16 pclock frequency, but the thing is that I often read that the Nvidia Riva TNT2 is ok to use for a mame station, I read that in advancemame website, in easymamecab http://easymamecab.mameworld.net/html/hardware.htm, in easymamecab they talk about the use of this card with advancemame. But i don't understand what advancemame could do that X couldn't do ? If I ask X to use a 15Khz resolution and it tells me that the card pclock can't handle this, why advancemame could be able to do this ? (i didn't tried advancemame because I really want to use X in order to make my own front-end)

So what I did wrong ?

Is it possible to use a TNT2 in order to have the right 15khz resolution for games ?

Is there any floppy disk or bootable cd that would produce a 15Khz video signal at boot so I can test ?

Is it possible to make X use the resolution most used by games, eg 320x224 ?

Have someone experienced the ranges that a standard resolution monitor can handle ? (i know it changes from a monitor to another, but is there a common range ? eg: hfreq can go from 14 to 16, vfreq from 55 to 65, i dunno ...)

Is there someone here who is as good as I am in Gyruss ?  

[wpcmame]

Try to double the horizontal resolution (i.e. double the pixelclock)

Advancemame can double the horizontal resolution for you but with other mame versions you probably need to double the vertical resolution as well.

The game picture will look exactly the same. i.e it doesn't matter if the resolution you use is 320x224, 640x224,  640x448 as long as the pixels are doubled.

If you want to experiment you can increase the horizontal size on the monitor by using the H.SIZE knob. Depending on your monitor you might be able to go down to 300 horizontal pixels with a 12MHz clock. My Hantarex can be adjusted so that only 32us is visible. With a 12MHz pixel clock that is 384 pixels.

[AMIGrAve]

I guess the doublescaned modeline should look to something like that

Modeline "368x248@60ds" 14.32 368 400 424 456 248 253 256 261 doublescan

But how could my monitor, which has a 7.16 clock freq according to http://www.klov.com/monitor.html, could handle a 14.32 pclock ??

Did you already started an X server on an arcade monitor ?

[desmatic]

Hi,

I just bought a Pit Fighter with a 15Khz screen inside.
I would like to use Linux for this mame station project.
I've got a nVidia Riva TNT2 and a Matrox Millenium G200.
I've generated a modeline with http://xtiming.sourceforge.net/cgi-bin/xtiming.pl
and the specifications I read at http://www.klov.com/monitor.html.

The modeline is :
Modeline "368x248@60" 7.16 368 400 424 456 248 253 256 261

Actually, I just wan't to make some tests, so I fired up knoppix, i added the modeline and tried to start X.
X won't start claiming that the pclock is too low for that gfx card. The MGA and the NVIDIA modules (i tried both cards) print in /var/log/Xfree86.0.log   -->  Clock range:  12.00 to 350.00 MHz , but it prints that for all my cards,

This is an artificial restriction placed by XFree86.  It's supprising they would do such a thing, given their "no policy" philosophy.  12mHz is the lowest VGA mode.  Try using 640x240.  That'll give you a pclock of 12 at 15kHz.

even for my Nvidia Geforce 2 mx in another computer.
If X think that the lowest pclock frequency for these cards is 12.0 then I understand that it refuses this modlines wich uses a 7.16 pclock frequency, but the thing is that I often read that the Nvidia Riva TNT2 is ok to use for a mame station, I read that in advancemame website, in easymamecab http://easymamecab.mameworld.net/html/hardware.htm, in easymamecab they talk about the use of this card with advancemame. But i don't understand what advancemame could do that X couldn't do ?

AdvanceMAME doesn't use the X server (though it can).  It uses the svgalib driver library or the kernel's framebuffer drivers.

If I ask X to use a 15Khz resolution and it tells me that the card pclock can't handle this, why advancemame could be able to do this ? (i didn't tried advancemame because I really want to use X in order to make my own front-end)

So what I did wrong ?

You did nothing wrong.  This is an artificial limitation imposed by X.  I don't know why it's their.  It deffinitely goes against their "enable hardware" and  "not enforce policy" philosophy.

Is it possible to use a TNT2 in order to have the right 15khz resolution for games ?

Yes, but you won't get a 15kHz console mode and you'll be restricted to a pclock of 8mHz or higher.

Is there any floppy disk or bootable cd that would produce a 15Khz video signal at boot so I can test ?

None that I'm aware of for Linux.  Though it would be a reatively easy task to make one.  I might add it to my todo list.

Is it possible to make X use the resolution most used by games, eg 320x224 ?

X is kind of a pain.  You have to create every modeline you need.  It's a lot of work and if you don't know what you are doing, the emulation may not be accurate.

Have someone experienced the ranges that a standard resolution monitor can handle ? (i know it changes from a monitor to another, but is there a common range ? eg: hfreq can go from 14 to 16, vfreq from 55 to 65, i dunno ...)

The only mode that seems to be common to them all is 320x240 at 15.72-15.5kHz x60Hz.  If you use a pclock to 12, then you end up with a mode that is both common to VGA cards and Arcade monitors, 640x240 (this is how ArcadeOS works).  

From the questions I get regularly, its very easy to tell that monitors vary widely in quality and capabiity.  It always sucks when I tell someone to do this that and the other to fix their problem and they come back and say their monitor can't.

Is there someone here who is as good as I am in Gyruss ?  

Undoubtably not, but I'm working on it :p

[desmatic]

I forgot to mention that the matrox cards generally support lower pclocks than nvida cards and they are easy to configure for a 15kHz console.  I updated my G400 page.  It now includes linux notes for booting a 15kHz console.  I'd be interested in hearing how well the G200 works.   It uses the same driver as the G400 so I suspect if it works, it will work very well.

And, as an aside, linux could deffinitely use a few more FEs.  Good luck with it.

[AMIGrAve]

First of all, thanks for this very complete answer, it has become more clear in my mind now, you also confirmed some thought I had but about which I was doubting.

This is an artificial restriction placed by XFree86

That's exactly what I tought when I saw that the clock range was the same for three gfx cards completly differents (perhaps only a few seconds because it seemed unrealistic to me that such a thing would be an X limitation). Then I had a silly idea yesterday, and after doing it, I realised it was not as silly as I tought. I often noticed that people often ask help about X configuration on forums, etc ... and they often attach their X log file. So I made a search on google with the keyword "Clock range:  12.00 to" I had 1710 hits on google.
Then I searched with the keyword "Clock range:  11.00 to" and I had 103 hits. "Clock range:  10.00 to" --> 82 hits and "Clock range: 9.00 to" 2  hits. I got nothing below (9Mhz dot clock matches ATI cards). Anyway, I believe you if you say that it's an X limitation, you seems to know a lot on this subject, and by the way, the modeline tutorial on your website is excellent, are you the author of this excellent piece of Free Documentation ! Anyway, you probably guessed that I didn't read it entirely otherwise I wouldn't be posting lame questions ;-) but of course I plan to read it carefully from the begining, if you are interested I can write a french traduction while I learn it.

Comming back to my question : even a  9Mhz pclock is still too low for the resolution needed by 15Khz games, so I'll give a try to the 640x240 resolution, I guess the modeline should look as somthing like this (i'll have to try 680x240 for my monitor) :
Modeline "680x240@60" 12.00 680 712 752 784 240 245 248 253

I'll try this as soon as I'll replace the brightness plot on my monitor.

I'm aware that the ArcadeVGA is from far the best solution, but as I already spent a lot of money I prefer to try this way first.

Is there any floppy disk or bootable cd that would produce a 15Khz video signal at boot so I can test ?

None that I'm aware of for Linux.  Though it would be a reatively easy task to make one.  I might add it to my todo list.

Wow, I guess that would be cool for all the mame cab community !
The best think would be a boot floppy (could be re-used for an eltorito boot cd for those who don't have floppy) that run a testing tool in 15Khz and the tool by the same occasion could be used to check geometry, colors, brightness, etc, only by displaying usefull gfx for this purpose)
Personnaly I only coded mode 13h in asm a long time ago so I don't know if I could be of any help, anyway, if I can do anything to help when your todolist will comme to this project, I would be happy to do so.

[desmatic]

First of all, thanks for this very complete answer, it has become more clear in my mind now, you also confirmed some thought I had but about which I was doubting.

This is an artificial restriction placed by XFree86

That's exactly what I tought when I saw that the clock range was the same for three gfx cards completly differents (perhaps only a few seconds because it seemed unrealistic to me that such a thing would be an X limitation). Then I had a silly idea yesterday, and after doing it, I realised it was not as silly as I tought. I often noticed that people often ask help about X configuration on forums, etc ... and they often attach their X log file. So I made a search on google with the keyword "Clock range:  12.00 to" I had 1710 hits on google.
Then I searched with the keyword "Clock range:  11.00 to" and I had 103 hits. "Clock range:  10.00 to" --> 82 hits and "Clock range: 9.00 to" 2  hits. I got nothing below (9Mhz dot clock matches ATI cards). Anyway, I believe you if you say that it's an X limitation, you seems to know a lot on this subject, and by the way, the modeline tutorial on your website is excellent, are you the author of this excellent piece of Free Documentation !

Thanks, it's still not finished yet though.  There are two pages that I have been meaning to add for a while.  Namely, a very advanced advv.exe page and a page for vertical on horizontal and vice versa.  A page dedicated to stretching techniques would be ultra groovy as well, but all this stuff takes time.

Anyway, you probably guessed that I didn't read it entirely otherwise I wouldn't be posting lame questions ;-)

It's a lot to digest, especially the last few pages.  www.howstuffworks.com is also an excellent source for crt info that might give you some good background info to make my tutorial easier to follow.

but of course I plan to read it carefully from the begining, if you are interested I can write a french traduction while I learn it.

That would be very groovy.   If you do so, don't worry overly about formatting.  I can work with anything you use, ms office, openoffice, txt, or whatever.

Comming back to my question : even a  9Mhz pclock is still too low for the resolution needed by 15Khz games, so I'll give a try to the 640x240 resolution, I guess the modeline should look as somthing like this (i'll have to try 680x240 for my monitor) :
Modeline "680x240@60" 12.00 680 712 752 784 240 245 248 253

I'll try this as soon as I'll replace the brightness plot on my monitor.

There is actually a vga pclock number, i think it's 12.5 but I can't recalll.  I'll search for it and post it when I find it.  If you use the right number, then the mode should work on any VGA video card.

I'm aware that the ArcadeVGA is from far the best solution, but as I already spent a lot of money I prefer to try this way first.

ArcadeVGA is an excellent solution.  It's just not meant for everyone.  Some like to tinker (like myself), others want more options (like myself).  When it comes to arcade monitors, sacrifices and comprimises MUST be made.  Andy made some excellent comprimises, however, if you don't like them, you'll need to use AdvanceMAME so that you can choose for yourself what you want to sacrifice.

Is there any floppy disk or bootable cd that would produce a 15Khz video signal at boot so I can test ?

None that I'm aware of for Linux.  Though it would be a reatively easy task to make one.  I might add it to my todo list.

Wow, I guess that would be cool for all the mame cab community !
The best think would be a boot floppy (could be re-used for an eltorito boot cd for those who don't have floppy) that run a testing tool in 15Khz and the tool by the same occasion could be used to check geometry, colors, brightness, etc, only by displaying usefull gfx for this purpose)
Personnaly I only coded mode 13h in asm a long time ago so I don't know if I could be of any help, anyway, if I can do anything to help when your todolist will comme to this project, I would be happy to do so.

Yes, I'm working on a MAME linux distro based on LFS and Gentoo.  It wil take some time though, maybe a month or so.  I'd like for there to be better more predictable video card support before it goes live though.

[AMIGrAve]

Thanks, it's still not finished yet though.  There are two pages that I have been meaning to add for a while.  Namely, a very advanced advv.exe page and a page for vertical on horizontal and vice versa.  A page dedicated to stretching techniques would be ultra groovy as well, but all this stuff takes time.

Are you using DOS for your mame cab ? (I ask because i see you talk about advv.EXE)

It's a lot to digest, especially the last few pages.  www.howstuffworks.com is also an excellent source for crt info that might give you some good background info to make my tutorial easier to follow.

Thanks for the link, didn't knew this web-site.

but of course I plan to read it carefully from the begining, if you are interested I can write a french traduction while I learn it.

That would be very groovy.  

I'm on it ! ;-)

There is actually a vga pclock number, i think it's 12.5 but I can't recalll.  I'll search for it and post it when I find it.  If you use the right number, then the mode should work on any VGA video card.

Well I bought another plot and replaced the broken one, so I could make tests. I made a 640x240 modeline and it worked as you can see on the attached screen-screenshot ;-) Anyway I still have to find the H-SIZE plotter in order to make the 640 pixels be displayed on the screen.

ArcadeVGA is an excellent solution.  It's just not meant for everyone.  Some like to tinker (like myself), others want more options (like myself).  When it comes to arcade monitors, sacrifices and comprimises MUST be made.  Andy made some excellent comprimises, however, if you don't like them, you'll need to use AdvanceMAME so that you can choose for yourself what you want to sacrifice.

Yeps, I guess i'll go for one, because I would like this station to use other emulators such as uae, dice, ... and these won't have the facilities that advancemame offer, so the only option I have is to buy an AracadeVGA.

[AMIGrAve]

I forgot to post the picture ;-)