midway arcade greatest hits mod?

[SMiTH]

deluxux brought this up a few weeks ago as an idea, and I have also thought about this mod in the past as well.
The midway arcade hits games for dreamcast could possibly be modded?
I think on the og xbox there was a mod for the midway games that added custom roms.
From what I remember they had to overwrite the rom data using hex data, it wasn't a rom swap.
I could be wrong but the roms used had to be smaller in size or exact due to using hex data?
(to not go over the size of the original roms)

I looked at the midway games for dc and never figured it out.

Maybe search the dc files for similar hex data to the original game roms used on the disc?
(compare each mame game rom hex data to dc files etc)
I tried this but, didn't put much time into it.

mame roms have many files in a zip from what i remember??
the data could use different endianness or maybe encrypted as well??
Has anyone tried to mod the game?

Lou_P had some info on what games might be compatible.

Midway arcade classics vol. 1 and vol. 2 are likely a emulators of the following boards.

Vol .1
board
WILLIAMS 6809 REV.1
Bubbles
Defender
Joust
Robotron
Sinistar
Defender II / Stargate

Compatible games:
https://www.system16.com/hardware.php?i ... =1044#1044

Vol. 2
Boards
Irem M-52 (moon patrol)
Compatible games
https://www.system16.com/hardware.php?id=736
Atari System 2 (paperboy and 720)
Compatible games
https://www.system16.com/hardware.php?id=769
Bally Midway MCR-Scroll (Spy Hunter)
Compatible games
https://www.system16.com/hardware.php?id=605
Atari Gauntlet (Gauntlet)
Compatible games
https://www.system16.com/hardware.php?id=766
Midway MCR-III (Rampage)
Compatible games:
https://www.system16.com/hardware.php?id=602

Just are early 80's games.
Just a little bit of information to someone could have this modding challenge

[SMiTH]

I found a few interesting things about midway 1.
Turns out what I thought was a mod on og xbox for midway games was not really a mod at all.
It was just game files that were unlockables on different disks and making a standalone.
None of it was for the midway games.

As for midway 1.
It is a wince game.
You can overwrite the data for roms.
The mame rom files are in plain hex.
I was correct about this being the case.
But, it leaves 2 unused mame rom files (unless this data is somewhere else or scrambled/encrypted)?

When overwriting the mame rom data the game does not crash.
I think this might be good because typically doing that would crash a game.
So I'm thinking that it has to do with those 2 files and possibly a line of hex code before the rom is loaded?
This line of hex code looks like what I have seen in save files that usually is encryption? (just guessing)
Either way it still is interesting.

As for midway 2 its totally different.
The file structure is different.
I have yet to really delve deeper.

I will post stuff about the findings later.

[SMiTH]

MIDWAY_1.EXE AND BUBBLES mame game rom:
The exe has the plain hex code for the game rom. (in this example bubbles.1b - bubbles.12b)
It represents bubbles.1b - bubbles.12b in the mame game rom archive.
In MIDWAY_1.EXE - start bubbles.1b @ 000b39c0
In MIDWAY_1.EXE - end bubbles.12b @ 000bfdc0

The 2 mame game rom files that are maybe scrambled/enc or elsewhere in the dc data are:
decoder.4
decoder.6

The sound data is in a .dat file for the dc : BUBSND.DAT
It is bubbles.snd in the mame rom archive.

Possible enc?? MIDWAY_1.EXE (hex code before bubbles game rom data) just guessing here??


I replaced the game bubbles with mame game rom splat!
Once at game selection screen after choosing bubbles game...
The game doesn't load.
I thought it freezes, but it doesn't.
No crash happens either.
So, I'm thinking its possible to figure this out?

[deluxux]

Very interesting stuff, Its got to be possible somehow. Its been done on other emulators, SSP, Check this TG16 emu on the PSP https://wololo.net/talk/viewtopic.php?f=24&t=41108 but also on the PS4 now with the PS2 emu.

[SMiTH]

Very interesting stuff, Its got to be possible somehow. Its been done on other emulators, SSP, Check this TG16 emu on the PSP https://wololo.net/talk/viewtopic.php?f=24&t=41108 but also on the PS4 now with the PS2 emu.

yes, i think its possible too.

overwrite the original game hex data with the custom rom hex data. (already proven that can be done)

whats left:
is there encryption before the rom loads?
is there other encrypted data?
are the 2 decoder files necessary for a game to work?
if they're needed, where does that get modified?
how to modify (extract/rebuild) the .dat containers that hold the snd data.

if those things are figured out, then i think its completely possible.

its possible other roms would work that are not using the same arcade boards.
i think the holy grail for bob dobbs will be a working tron arcade game
hopefully someone decides to take a look at this potential mod.

[SMiTH]

Midway 2 is a wince game.
File structure is similar to pc version.
Hex is different since its written for pc and not dc. (at least for the exe and dll files)
rom files seem to be the same?

.dll files on dc version are .exe files on pc version.
the strings for the rom files are present. (in pc exe's and dc dll's)
the rom files on pc version might swap to dc version?
sound files will still be an issue since dc version uses dat containers.

[SMiTH]

Midway 2

Keeping the sound files will cause the rom not to load. (this is true with midway 1 as well)
The dc .dll files are .exe files on pc. (they have the strings for loading files)
The menu.exe on dc midway 2 also has the strings for loading files.

I modified the dc version to use less data and edited the strings in menu.exe and .dll's (for directories, remove sound files, etc)
This allowed swapping the rom (.inf) files from pc version.
The other rom files that are not .inf can also be swapped. (other arcade cabs, not rampage, not moon patrol)
The pc version used is the original win95 version.

I tried using the rampage arcade cab to load inf files but it resulted in either a black screen or a vmu error message.
The only arcade cab that would load the inf files without a vmu error message was moon patrol.

*The vmu error message might be a good thing as its trying to load the rom and its compatible?
**Vmu error screens variations (grey screen, purple screen, black screen)

I also tried swapping other arcade cabs with other roms from pc version and since there are a few different rom files it results in a black screen. (not all)
Vindicators rom files closely resemble the 720 rom files and there are a few other roms that are close to the other arcade cabs used as well.
Maybe someone can figure this out?
I still think its possible to mod the midway games, but its not something I can figure out. (currently? or ever lol)

Here are the results of vindicators roms swapped for 720 roms :



Here are the results of loading inf files with rampage arcade cab :



Here are the results of loading inf files with moon patrol arcade cab :



Here is the vmu error message (variations are: grey screen, purple screen, black screen) :

[SMiTH]

If anyone wants to try modding i've included:

plain files
midway pc roms from the win95 version (.inf files, .rom files)
selfboot cdi

(the only arcade cabs you can use to load roms are 720, rampage, moon patrol)
(.inf files are for moon patrol cab and rampage cab)
(.rom files are for 720 cab)

example of the rom files:
Alpha, descrmmu, fixedcpu, mobrom, pfrom, etc

sound data, & other arcade cabs have been removed.

https://mega.nz/file/BEZgzLrC#3o3nu2HZS ... DLUeaFzjfM