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twistedsymphony

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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?
 
I thought P47 had a different motherboard regarding connectors spacing making it impossible to plug a different romboard.

Also I've never had a look at the protection.
 
The protection lies in a BPROM located on motherboard, each game has its own data, see MAME source for reference and this page :

http://arcade-area.lebonforum.com/t...m-1-compatibilite-entre-les-jeux-du-systeme-a

Other than this, it's a simple ROM swap (but like Apocalypse says, the P47 ROM board is unique so its not a compatible donor)

P.S.
Recently I have adapted the Phantasm BPROM in GAL since a friend of mine has a motherboard with this missing BPROM.I think it can be done with all other BPROMs of other Mega System 1 games.
 
from the pictures I've posted the P47 ROM board is clearly unique, I know this already which is why I'm looking for a different ROM board to attempt a conversion.

but is the P47 main board also unique?
Only connectors spacing is different, functionally speaking they are identical.
 
connectors spacing is different
damn, that sucks :( the main board seem difficult to find all I ever see for sale are the ROM boards I was hoping P47 would have been useful for rom board swapping.


Recently I have adapted the Phantasm BPROM in GAL since a friend of mine has a motherboard with this missing BPROM.I think it can be done with all other BPROMs of other Mega System 1 games.
I was thinking about this... if the security can be duplicated in a GAL then that means a potential multi could use unpatched ROMs, no?
 
I was thinking about this... if the security can be duplicated in a GAL then that means a potential multi could use unpatched ROMs, no?
Absolutely. We could even use a bigger GAL chip, store all the different security combinations needed and select which one to use with some combinatory logic on unused pins of the GAL chip.
 
Hi guys,

I've already done some Mega System 1 conversions in the past.

The BPROM is not the only thing to swap, there is a protection chip on every rom board labeled M50747. It is noted "Encryption (key #)" on the MAME source code. Fortunately there are only 3 different keys (2 are truly interesting), allowing to use the same protection chip for some games.
Anyway, a ROM patch would be needed if you want to make a multi-board.

Also, according to the MAME source code, on the last games (the ones built of only one board), protection looks like to be related to the inputs (probably a custom input chip for each game ?) Didn't try converting those ones.
 
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there are only 3 different keys (2 are truly interesting)
Sorry I don't speak Japanese so the 3 are interesting to me.

I've got some conversions ready (It was normal to have a look after Mega system 32, wasn't it?).
Looking for real hardware or testers (let the nightmare begin again ;) ).
 
Only connectors spacing is different, functionally speaking they are identical.
So I took a gamble and bought some ROM boards for Mega System 1 to try on my P-47 main board and they work... the connector spacing is identical.

In addition to P-47 I've got Rod Land, and Jitsuryoku Pro Yakyuu and both ROM boards fit and boot on the P-47 main board.

I also picked up a Kick-Off ROM board and while the PCB connector spacing is identical it looks like someone swapped the connectors on the rom board with some generic headers that don't mate with the connectors on the main board (main board connectors have a keyed shroud, this rom board's connectors are too bulky around the parameter to fit into the shroud.

So with that said P-47 seems to be a suitable donor for the main board (the ROM board likely can't be converted to anything else) And I've got a few ROM boards I could use to test conversions.
 
@twistedsymphony Very interesting I would have bet P47 was different. Even Caius confirmed it. Maybe there are more than one revision of the boards for this game.
 
I had to order some 27c512 EPROMs for this as it seems most games use a few of these. I got them in yesterday so I attempted to convert my Jitsuryoku Pro Yakyuu to Plus Alpha. This involved adding a whole bunch of sockets to the ROM board as Plus Alpha uses all but one ROM location and JPY uses only a few. Plus Alpha uses 5x 27c512 and 17x 27c010 I'm fairly certain it doesn't uses the non-jedec 27c301 pinout as the original ROMs I removed used the 27c010 pinout.

The board is also missing all of the ceramic caps that accompany each of the unused slots: 104Z (0.1uF) 25V. There are also 8x 0ohm resistor Jumpers on this ROM board. In JPY every one of these jumpers is closed.

I started looking for ROM board photos of Plus Alpha to see if I could determine the Jumper configuration... this was the best photo I could find:plus_alpha.jpg


for reference this is the JPY ROM board:
pro_yakuu.jpg

aside from the obvious ROM differences I quickly noticed that the JPY ROM board has 2 PALs that are not present on the Plus Alpha ROM board... And not just unpopulated... the boards are different Plus Alpha is "MB8845" labeled PCB and JPY is "MB-M02A" labeled PCB.

Searching around for photos of other games I discovered pictures of Saint Dragon on both an "MB8845" and on an "MB-M02" ROM board (which looks indistinguishable from an MB-M02A) so I'm assuming these are all just revisions of the same board. Saint Dragon and Plus alpha have all 8 of the jumpers open on every PCB photo I've found.

I tried with the jumpers closed first and got some sprite issues. I then removed them all and the sprite issues remained. Audio and gameplay seem to work great though.
pa_sprite.jpg


Just to see what would happen I tried running P-47 with the JPY Key chip... it plays normally but there are some sprite priority issues, other wise it's fine.


---------
After all of that above... swapping the boards around I accidentally installed the JPY key chip in backwards.
banghead.gif

for reference if you see a completely red screen on boot it means the keychip is backwards. it got burning hot and I started to smell the typical electronics burning before I managed to shut it down.

I let it cool and it seems to still work but it get hot now so I suspect it's not long for this world :(
I believe I read that these chips are just PALs so if anyone knows how to reproduce these I'd love to hear about it.
 

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Recently I have adapted the Phantasm BPROM in GAL since a friend of mine has a motherboard with this missing BPROM.I think it can be done with all other BPROMs of other Mega System 1 games.
@caius I recently bought a Lord of King ROM board and it seems as though the BPROM (CRC 85b30ac4) went missing somewhere before it arrived :( I was wondering if you'd be able to adapt that one in GAL form?

I think that particular BPROM would be quite useful recreated as it seems to be the most common and according to the link you posted above is compatible with:
-Shingen Samurai-Fighter
-Ninja Kazan
-Iga Ninjyutsuden
-Saint Dragon
-Earth Defense Force
-The Lord of King/Astyanax
-Jitsuryoku !! Pro Yakyuu
-Plus Alpha
 
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Since I haven't got anywhere with Plus Alpha conversion I started playing around with MAME and the Type-C pcb.

I'd like to find a Type-C pcb to play those games. They seem to use "Inputs" security. Doing a ROM swap in MAME (cybattlr ROMs on bigstrik PCB) it seems to boot but dumps me to the test screen where it shows all the dip switches as ON.

Looking at MAME source it seems each game has a unique string of numbers it provides to the MCU for the inputs. I'm assuming the MCU is unique per game... and sadly un-dumped :(

I wonder if it's possible to to patch out the security, or at least patch the ROM so that the the input codes to match the MCU on the donor board.
 
So! I've got Plus Alpha completely working now. Thanks to @Hammy for this comment that pointed me in the right direction:

As you can see, the encryption is on the GFX, Some sets have unencrypted GFX sets available etc.
It seems things have come full circle and it's back to that that point in time for your mega system 1 travels
So I think there are two things going on here. it looks like the program ROMs are encrypted and in addition to that the Sprite and Scroll0 ROMs are "scrambled" (meaning address and data pins on the ROMs are swapped) on Pro Yakyuu. So in order for Plus Alpha to work on the Pro Yakyuu ROM board I had to scramble it's sprite and scroll0 ROMs. Pro Yakyuu uses the same program ROM encryption as Plus Alpha so that works the same.

it also looks like Pro Yakyuu used 1 4Mbit ROM for each of these while Plus Alpha used 4x 1Mbit ROMs... so Since I didn't feel like scrambling 8 ROMs I joined them together and just scrambled the two. This also save you from having to install a bunch of Sockets on the Pro Yakyuu ROM board.

If anyone is interested here are scrambled Plus Alpha ROMs for use on a Pro Yakyuu ROM board:
https://mega.nz/#!wvYSSKbS!r0BoV592JQ9k0-vt3T6HK5uS7uk20-ZNcEE9xbZX4m4

The scrambling is just swapping 2 sets of data lines and 2 sets of address lines on each chip, I believe it could have been remedied with a replacement PAL, but where the PALs on this aren't dumped scrambling the ROMs was the easier option.

If you use these you'll want to make sure JP3 and JP4 are installed for the Scroll0 ROM and that JP7 and JP8 are installed for the Sprite ROM.

When using the rest of the Plus Alpha ROMs from MAME you'll want to remove the rest of the Jumpers, HOWEVER if you decide to join the Plus Alpha ROMs together you can leave the jumpers in place. JP1 and JP2 are for the sample ROMs and JP5 and JP6 are for the Scroll1 ROMs

leaving the jumpers in place allows you to use a single Large ROM, removing them requires you use multiple smaller ROMs.
 
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Thanks :)

Maybe you can give me some tips on dealing with encryption... I'm looking at the encryption setup here:
https://github.com/mamedev/mame/blob/master/src/mame/machine/jalcrpt.cpp

Is there a way to get MAME to decrypt or re-encrypt ROM data? or maybe there are some tools available that helps with this?

I'd like to play around with getting some "Key 1" encrypted game to work on a "Key 2" PCB and visa-versa.
 
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