What's new
By:
Filters

Wargods CF and Boot Rom

Screenshot 2023-10-06 at 13.32.04.png
Screenshot 2023-10-06 at 14.02.11.png


"I don't think limits" - Usain Bolt
 
@neku is the hero we need!

What did you do? That CHD is clearly different, and here I was thinking it would be the boot rom that needed adjustment.

1696597788341.png
 
ekorz said:
What did you do? That CHD is clearly different, and here I was thinking it would be the boot rom that needed adjustment.
Click to expand...
The CHD is different to show that it's not using the geometry of the original one but it's totally arbitrary geometry.

I figured out the only reason the game was not starting is changes in the geometry of the disk.
Simply adding a cylinder more which should not impact LBA <-> CHS conversion and it was refusing to boot/crash.
Meaning is was definitely asking the drive it's geometry and it was not hard coded.
I dumped every ATA transaction and found that on a normal run (with the right drive) it was calling "Identify Device (ECh)" ATA command and stored the geometry in memory.
This happens two times, the first time when bootsector.bin is ran and the second time when the game code boots.

The check validating the hard drive is the following:

Code: 
(((NCylinder * NHead * NSectors) >> 2) + 0xFF) >> 8 == 0x323

This check is done a first time after loading bootsector.bin and after reading the first game code sector.
Then every time a sector is read once the game code is running (from a different function).

Hot patching the memory with the right values and voilà, the game runs with any disk geometry without impacting the LBA to CHS conversion function.
From there i figured out what instructions can be rewritten to permanently patch it.

The bootrom is untouched, everything happens in the bootsector.bin and the game code which are stored in the hdd.

I am finishing to patch the hdd and will upload it.
 
Huge shoutout to @neku for doing this!

I appreciate the hell out of you!

Now, for anyone who has this board, I need some advice.

I recently got this board, but when I hook it to my supergun, I get no picture. I do have lights on the board but am I missing something here?

My supergun is outputting to composite since I can't test on my cab due to me only having one working arm right now from surgery. I should at least be getting the screen where it says no hard drive detected right?
 
I actually have a War Gods I need to sell. but yes I was always under the impression the hard drive security mechanism with these was simply CHS.

if there's any code changes I need to make, if you could kindly oblige in sharing that would be cool. for scientific purposes.
 
davesarcades said:
SummitArcade makes HDD's and CHD's for WarGods, has for years.
Click to expand...
From my understanding, those require specific CF cards or HDD capable of handling the SET MAX ADDRESS (F9h) ATA command to limit the maximum usable sectors announced in the IDENTIFY DEVICE command (ECh) to 822.016 sectors.

The patch i am working on modifies the boot and game code to bypass that validation opening the possibility to use any drive.
 
neku said:
From my understanding, those require specific CF cards or HDD capable of handling the SET MAX ADDRESS (F9h) ATA command to limit the maximum usable sectors announced in the IDENTIFY DEVICE command (ECh) to 822.016 sectors.

The patch i am working on modifies the boot and game code to bypass that validation opening the possibility to use any drive.
Click to expand...
Correct. Also Summit hasn't logged in here in a while and as of his last post didn't have any compatible CF cards left.

This is a win!
Any drive for Wargods, finally.
 
Ah, gotcha. I have a few if it helps. Bought from Summit. Both HDD's and CHD's.
 
Ya'll talked him up. Lol. Brandon is a career military man. Teaching the next generation of pilots to not suck is more important.

Great to see you here tho, man!
 
I wonder if something similar can be done for Area 51 Site 4, as it’s another Atari/Midway game with no working CF solution to date 👍
 
DRAGONKZ said:
I wonder if something similar can be done for Area 51 Site 4, as it’s another Atari/Midway game with no working CF solution to date 👍
Click to expand...
CFs don't work but other SSDs do... I don't think it has anything to do with the size so much as the speed of the device.
 
Thanks to @ekorz for the advice, I figured out my Wargods board issue...

Two rows of dipswitches on the board; switch 1 on both rows must be turned on for me to get a picture in any output.

I will get a 2GB card delivered hopefully tomorrow and I can try the patch out on my board.

I think that is the sweet spot in CF cards right now and available since CF's I've seen lower than 2GB have been sold for the same price as 2GB or they are cheaper but used on ebay with shipping adding up to the same price. And CF's from china take forever to get here.
 
DRAGONKZ said:
I wonder if something similar can be done for Area 51 Site 4, as it’s another Atari/Midway game with no working CF solution to date 👍
Click to expand...
gamefixer was actually able to get CF working on Site 4 a few months ago. I was under the impression they only worked with SD cards or something. I'm uncertain what type of adapter was used. I've never actually made one of those before.
 
You must log in or register to reply here.
Back
Top