You are not logged in.

#1 2011-09-18 10:31:42

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,849

Arcade cabinet and 15khz modes on xf86-video-intel 945GM?

I've an old arcade cabinet which i use to play with from time to time.
Inside it there's an old and scary pc with an arcadevga (radeon) card which does a great job in outputting 15khz modelines to the crt screen.
I was wondering if i can use a netbook in place of it; specifically an asus 1005ha which has a 945GM chipset.
By now,i just tried to plug the vga cable in the netbook and added a modeline that way:

xrandr --newmode "640x240" 13.220 640 672 736 832 240 243 246 265 -hsync -vsync
xrandr --addmode VGA1 640x240
xrandr --output VGA1 --auto
xrandr --output VGA1 --mode 640x240

The modeline should be right and fits into the TV frequency range,
but unfortunately nothing happened; it seems that the mode is out of sync and the crt stays black.

Somebody has a clue on what could be the cause? Maybe a software kms issue or a chipset limit on dealing with lowres frequencies?

Thanks.

Offline

#2 2011-09-23 00:27:02

kilgore70809
Member
Registered: 2011-09-14
Posts: 4

Re: Arcade cabinet and 15khz modes on xf86-video-intel 945GM?

It has been awhile since I played with Mame.. but if I recall correctly.  In order to use that 15khz monitor, you need to use a graphics card that can address it.  I don't think the laptop can do that, so that is why it's blank screen..

I remember an uber cheap card available to hit the 15khz range for PC...

Good luck!

Offline

#3 2011-09-23 09:54:38

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,849

Re: Arcade cabinet and 15khz modes on xf86-video-intel 945GM?

I searched further, and found that the problem lies in the kms code itself.
Seems like intel kms code (in kernel sources) contains some limits about lower dotclocks, but seems that somebody patched it and recompiled with success.
i managed to have 1024x320@60hz/15.5khz modeline working btw smile

Other issues like interlacing remains, but that should be just a driver issue.

Offline

Board footer

Powered by FluxBB