Main > Monitor/Video Forum
Idea: customized videocard BIOS
b3atmania:
Given that:
- The excellent ArcadeVGA card is made from off-the-shelf components driven by a customized BIOS.
- Many cards can do the same thing by tweaked video registers (as AdvancedMAME does).
What is stopping us making a replacement BIOS for common video cards? I would be happy to volunteer creation of a "generic" BIOS for outputting 15kHz signals. I think I have enough x86 assembly language knowledge on to get this done. The functional spec for the "universal" BIOS would be:
- Output in 15kHz on boot for TV and standard resolution monitors.
- Output in 25kHz on boot for medium resolution monitors.
- Output in 31kHz on boot for VGA and tri-sync monitors.
- Implement VESA BIOS calls with as much arcade resolutions as possible for both 15kHz, 25kHz and 31kHz.
Let's discuss how to go about this:
- As a starting point: is a dump of the ArcadeVGA BIOS available?
- Is the ArcadeVGA BIOS copyrighted? Would Andy be willing to release the BIOS source code, perhaps under a licence such as the GPL?
- Another good reference will be SVGALib and AdvancedMAME since many cards work with that setup.
I welcome feedback on this idea. Some issues to sort out are how to replace a BIOS in a card. I noticed some cards have the BIOS ROM in a socket while others have a flash upgradable BIOS. Flash upgradable would obviously be the most convenient. For testing purposes it is not necessary to replace the ROM on the card though.
Please note that I am not starting a commercial project. I fully intent to release source code and/or documentation of the effort.
SirPeale:
Andy has stated many times that the AVGA isn't just a stock card with a custom BIOS.
MonitorGuru:
>:( :police: Well first, any attempt to dump the ArcadeVGA BIOS would involve copyright infringement and therefore is ILLEGAL :police: >:(
Second, why would someone who has taken the time to find a series of card that would work, edit the bios, then package and sell the product, suddenly want to GIVE IT AWAY to competition (free source) to kill their business model? ???
But barring that (copying or asking for help from them), there is nothing illegal/immoral about simply doing the same work yourself and making it available for everyone.
I've considered the same thing, but there is so little information out there to modify video card BIOS'es (other than hacking them to get faster speeds/etc...) that I have given up attempting to do it as a personal project.
Also, I think, while convient, the ArcadeVGA is overrated. If only we could control the video card's output during POST and boot, then (almost) any card can be used to drive a VGA monitor once loaded by doing it all in software, instead of firmware. However it's the post/boot that is the major problem. Solve that and you don't have to do the entire solution, making it a much easier process.
wpcmame:
--- Quote from: Peale on March 07, 2005, 09:59:23 am ---Andy has stated many times that the AVGA isn't just a stock card with a custom BIOS.
--- End quote ---
That was true for the old 7000 based since that had extra hardware. AFAIK the new 9200 is a stock card with maybe a different hardware signature to prevent somone from just copying the bios.
I think the main problem with a customized videocard bios is legal. Just changing some display timings and add a few modes will most likely trigger ATI's (or another board manufacturer's) legal department.
Writing a comlete bios for the RV chip isn't an easy task without proper documentation. It will be even more difficult to get the bios ready while the card is still available to buy.
b3atmania:
--- Quote ---That was true for the old 7000 based since that had extra hardware. AFAIK the new 9200 is a stock card with maybe a different hardware signature to prevent somone from just copying the bios.
--- End quote ---
A different hardware signature is not gonna prevent copying. In DOS a VGA-compatible card has its BIOS hardwired at address C000:0000. It is trivial to dump the BIOS in DOS mode.
--- Quote ---I think the main problem with a customized videocard bios is legal. Just changing some display timings and add a few modes will most likely trigger ATI's (or another board manufacturer's) legal department.
--- End quote ---
The legal issue is further complicated by where you live. I am located in Europe where I can legally patch any software. The EU allows this to prevent vendor lock in and to ensure interoperability. Now, many videocard manufactors deny us interoperability with 15/25kHz RGB monitors. Ofcourse, manufactors are not required by EU law to provide assistence getting their product to work with 15/25 KHz RGB monitors. In this case EU-law grants me the option of fixing it myself. Someone living in the USA is probably out of luck as the DMCA prevents them from achieving interoperability in a legal manner.
--- Quote ---Writing a comlete bios for the RV chip isn't an easy task without proper documentation. It will be even more difficult to get the bios ready while the card is still available to buy.
--- End quote ---
Docs for many chipset and cards are available, witness XFree86 and AdvancedMAME.