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Jaleco Mega System 1 Conversions? or Multi?

It's twice the work to re-encrypt it. For the multi it's gonna need all unscrambled GFX roms and decrypted game program.

Try and disable the chip and get something like P47 running ;)

Not exactly sure how the encryption works without running mame and checking it out
 
I would think the ideal setup would be to decrypt/unscramble everything and get it running on the P-47 ROM board since that has no MCU at all and would greatly simplify the setup for a multi.
 
Yep, the only parts of note on the p47 rom boards is the strange mask roms and the 2 oki's
It's a 'good base to start' for making the multi... but multi will be a completely new top board (good that oki's are common)

but not a good board to convert due to the chips mask roms used.
Running the games in mame seems to show the decrypted code (at least for phantasm, what i have loaded)

PS: do you have a p47? if yes, can you tell me if rom 13 is a mask or eprom :)
 
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twistedsymphony said:
I learned about the Jaleco Mega System 1 when I first started picking up Jaleco Mega System 32 games it's got a pretty varied catalog with some great shmups and platformer/rpgs.

it looks as though you can swap out the ROM board similar to System 16 or System GX. Looking at MAME source there seems to be a few rom board variations duplicate protection keys across games, which to me says that straight conversions without patching might be possible for some games.

Code: 
Year + Game                       System    Protection
---------------------------------------------------------------------
88  Legend of Makai (World) /       Z
    Makai Densetsu  (Japan)         Z
    P-47  (World) /                 A
    P-47  (Japan) /                 A
    P-47  (Japan, Export)           A
    Kick Off (Japan)                A
    Takeda Shingen (Japan)          A             Encryption (key 1)
    Ninja Kazan (World) /           A       Yes + Encryption (key 1)
    Iga Ninjyutsuden (Japan)        A       Yes + Encryption (key 1)
89  Astyanax          (World) /     A       Yes + Encryption (key 2)
    The Lord of King  (Japan)       A       Yes + Encryption (key 2)
    Hachoo!                         A       Yes + Encryption (key 2)
    Jitsuryoku!! Pro Yakyuu (Japan) A       Yes + Encryption (key 2)
    Plus Alpha                      A       Yes + Encryption (key 2)
    Saint Dragon                    A       Yes + Encryption (key 1)
90  RodLand  (World, set 1) /       A             Encryption (key 3)
    RodLand  (World, set 2)         A             Encryption (key 2)
    RodLand  (Japan)                A             Encryption (key 2)
    R&T (Prototype?)                A             Encryption (key 2)
    Phantasm        (Japan) /       A             Encryption (key 1)
91  Avenging Spirit (World)         B       Inputs
    Earth Defense Force (Prototype) A             Encryption (key 1)
    Earth Defense Force             B       Inputs
    64th Street  (World) /          C       Inputs
    64th Street  (Japan)            C       Inputs
92  Soldam (Japan)                  A             Encryption (key 2)
    Big Striker                     C       Inputs
93  Chimera Beast                   C       Inputs
    Cybattler                       C       Inputs
    Hayaoshi Quiz Ouza Ketteisen    B       Inputs
    Peek-a-Boo!                     D       Inputs
I recently picked up a P-47 board set for a reasonable price (great game too!) and would love to try out some conversions for some of the more difficult to find titles.

Some photos for reference:

P-47 Main board plus ROM board (system "A" no protection):
p47.jpg

pro yakuu ROM board (system "A" encryption key "2"):
pro_yakuu.jpg

rod land ROM board (system "A" encryption key "2"):
rod_land.jpg

plus alpha ROM board (system "A" encryption key "2"):
plus_alpha.jpg'

Has anyone attempted or seen a conversion on this system? I'm currently searching for a donor ROM board to experiment with but I'm curious if anyone else has tried this or if there are any gotchas?
Click to expand...
Does anyone know which other Jaleco games that uses the MB8845 ROM board, the one that is used by Plus Alpha?
 
frsj8112 said:
Does anyone know which other Jaleco games that uses the MB8845 ROM board, the one that is used by Plus Alpha?
Click to expand...
ROM board is irrelevant, there's only 2 (maybe 3?) ROM board used by Mega System 1A, if you're trying to make a conversion what matters is the protection key. As long as you're using a board that has the correct key it's just a ROM swap, and maybe some address remapping.

This is all covered in my posts back on page 1 of this thread.
 
twistedsymphony said:
ROM board is irrelevant, there's only 2 (maybe 3?) ROM board used by Mega System 1A, if you're trying to make a conversion what matters is the protection key. As long as you're using a board that has the correct key it's just a ROM swap, and maybe some address remapping.

This is all covered in my posts back on page 1 of this thread.
Click to expand...
And the protection key is what, is it an IC on the romboard or is it the PAL chip on the baseboard at location M14?
 
How does the "protection" work on Rodland? I have gotten a pcb for repair which initially played with garbled backgrounds and all character sprites stacked on top in a vertical line.
the garbled backgrounds was a loose pin on one of the 6 bigger customs on the motherboard, and now the backgrounds are perfectly fine, and flowers are also correct, but there are no sprites whatsoever. The rom board is a original rodland, but the motherboard looks like it could be from another jaleco game... the protection prom has a small halfmoon sticker with handwritten R.R on it.

(the sprite rom seems fine and dump matching in mame world set 2)

Before I look any further I thought I might ask if this is the protection kickin in? hiding all the sprites?

Thanks!
 
MetalliC said:
it does have encrypted: 1st background, sprites, main program.
Click to expand...
Correct, the MCU also does a few work ram tasks.

The scrambling is most often done by the MCU in conjunction with the undumped GAL chips that are different on each game.
 
As the multi comes out the romboards will drop in price so sending one for a decap will be a little easier.
Maybe someone will offer it up (i don't own any of that type originals)
The gal dumps are also needed for all games :(

As for the functions, it can be bypassed with some LS chips simulating what it does so dead MCU can be repaired.
As for mame etc, the implementation is as good as it's gonna get without the dumps.
The IRQ problems are not too bad to fix but i'm not sure how to convey this info to the mame team (my "C" code / modern lingo sucks).
 
Hammy said:
As the multi comes out the romboards will drop in price so sending one for a decap will be a little easier.
Click to expand...
I don't think this is a problem, at least some time ago I've seen at YAJ MS1 ROM boards like Saint Dragon etc and they was quite affordable, like few dozen bucks. it is usually the problem to find the person who can and will to do decap/RE work.
 
MetalliC said:
it does have encrypted: 1st background, sprites, main program.
Click to expand...

Thanks :). In my case it was a SRAM socket that was bad and some busted solderjoints on one of the SIL customs.. really dont like those big flimsy ceramic customs.
 
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