Metro VG420 Multi interest and development thread?

[twistedsymphony]

I'm nearing completion of a Multi-board for the Metro VG420 hardware.

Why this hardware? Why make this multi?
Well I really wanted Sky Alert and Karate Tournament, both very expensive PCBs, and I wanted to figure out how to convert a cheap Toride PCB to either of these games. I managed to do it but it required some additional circuitry to do so and that additional circuitry was most of the way to a multi, all I needed was some bigger ROMs and a way to bank switch them. So I decided that since the hard work was already done I might as well take it the rest of the way and make a full multi.

(final V2.2 PCB)

Spoiler

(Prototype V2.1 PCB)

Games this will play:

• The Karate Tournament
  
  
  
• Lady Killer
  
  
  
• Poitto! (Rev D)
  
  
  
• Sky Alert
  
  
  
• PangPom's
  
  
  
• Last Fortress - Toride (JP Version)
  
  
  
• Last Fortress - Toride (CN Rev C "Adult" Version)
  
  
  
• Last Fortress - Toride (Korea Version)
  
  
  

All game above use original unmodified code, except for those ported to the VG420 hardware, which required patches for input control remapping but are otherwise unmodified.

Donor Boards for this = any "VG420" PCB which includes:

• Last Fortress - Toride (VG240 Versions) [confirmed working donor]
• PangPom's [will hope to confirm as a donor soon]
• Sky Alert [theoretically should work, I don't have one to test but if you own this game I'd recommend just buying a cheap Toride as a donor instead]

They look like this (note the large VG420 text on the bottom of the pcb):

Pricing
$87 = DIY Kit, includes PCBs and all parts (minus EPROMs) necessary to solder together the multi
+$14 = Optional Rotary switch in place of standard DIP Switch selector
+$43 = EPROMs necessary for the kit (4x 27C322, 3x27C160, 1x27C801)
+Shipping = (Varies based on your location, anticipated ~$15 in the USA ~$25 internationally)
*Note: it's unclear how import tariffs may effect pricing going forward so actual pricing may change

Instructions and Tools
User Guide: https://bit-district.com/docs/MVG420-M8 v2.2 User Guide 2025-04-15.pdf
Build Tools: https://bit-district.com/docs/MVG420-M8_v2.2_build_tools_2025-04-15.zip

Interest List:
0. Ekorz - Shipped
1. XtraSmiley - Searching for Donor
2. ForestOfDreams - Shipped
3. Mageta the Lion - Shipped
4. djsheep - Searching for Donor
5. Hammy - Pending
6. Darksoft - Searching for Donor
7. plasticfactory - Searching for Donor
8. bodgit (DIY) - Searching for Donor
9. AlxUnderBase (DIY) - Searching for Donor
10. JohnRambo'sKnife - Searching for Donor

OLDER PRE PRODUCTION IMAGES:

Spoiler

("paper" prototype to check alignment)

(render from production)

ORIGINAL POST:

Spoiler

I'm working on a project for the various Metro VG240 and VG460 PCBs. The last piece of this puzzle is figuring out PangPom's

Ideally I'd like to buy or borrow a PangPom's PCB so I can work out the differences between that game and other games on this hardware. (found)

I do also have a hand-crafted PLD that It think will work as a replacement on this PCB so if you have one and don't want me to borrow but do have the ability to program GAL16V8s I'd love to have you test that for me and it would actually be a small help.

I don't usually like to post about my projects until they're done but I think there's probably low interest in this so...

Basically I worked out a few conversions on this hardware but it's not exactly clean:

(This is Karate Tournament on a VG420 Toride PCB)

BUT, I figured making a nice plug in circuit was most of the way to a multi So I did that

Hardware and everything is all designed and ready to be sent to fab but I don't have PangPom's working and I'd like to figure that out before spending the money on prototyping this PCB in-case there are additional changes that need to be made to support it.

So yeah, if you can find me a PangPom's for sale or have one you'd be willing to let me borrow that would be greatly appreciated and help me complete this project (found)

 

[twistedsymphony]

Thanks to @Mageta the Lion for pointing me to a listing for a PangPom's!

I'll use this thread to post updates once I have more.

 

[twistedsymphony]

INFO moved to first post

Spoiler

I got some questions over PM so I figured I'd answer here:

Donor Boards for this = any "VG420" PCB which includes:

• Last Fortress - Toride (VG240 Versions) [confirmed working donor]
• PangPom's [will hope to confirm as a donor soon]
• Sky Alert [theoretically should work, I don't have one to test but if you own this game I'd recommend just buying a cheap Toride as a donor instead]

They look like this:

(note the big VG420 text at the bottom)


Games this will play:

• PangPom's [confirmed working, unmodified]
• Last Fortress - Toride (JP Version) [confirmed working, unmodified]
• Last Fortress - Toride (CN Rev C "Adult" Version) [confirmed working, unmodified]
• Last Fortress - Toride (KO Version) [confirmed working, unmodified]
• Sky Alert [confirmed working, unmodified]
• Poitto! (Rev D) [partially working, IRQ and controls need to be patched]
• Lady Killer [confirmed working w/patched controls]
• Karate Tournament [confirmed working w/patched controls]

 

[XtraSmiley]

Sky Alert looks cool and I might be the only person who likes my Lady Killer game... so yes, if I can find a donor!

 

[ForestOfDreams]

I am in for this one.
Little known fact guy who made strider helped create karate tournament.
Pang poms and Sky Alert look fun too.

 

[Mageta the Lion]

Ok, which of you fellows bought the Toride on eBay i was trying to low-ball the seller on

 

[djsheep]

Am unfamiliar with this hardware, but looks fantastic... if I ever get a cheap donor, I'd be all over this!

 

[twistedsymphony]

As a fan of Puzzle games I've always loved the Metro hardware.
There are a few generations of this hardware, each with slightly different audio CPU and an upgraded VPU (Video Processing Unit) making a truly universal multi impossible.

Since System16 doesn't list Metro, here are all the different Metro hardware platforms that they made:

VG420 Hardware [i4100 VPU, uPD7810 Audio CPU, YM2413+M6295 Sampler]

• Last Fortress - Toride (VG420 Version)
• PangPom's
• Sky Alert

VG460 Hardware [i4100 VPU, uPD7810 Audio CPU, YM2413+M6295 Sampler]

• Last Fortress - Toride (VG460 Version)
• Lady Killer
• Karate Tournament

MT5260 Hardware
(despite these all using the same physical PCBs the VPU and audio chips used are very different game to game)
[i4100 VPU, YM2413+M6295 Sampler]

• Poitto!

[i4200 VPU, YM2413+M6295 Sampler]

• Dharma Doujou
• Torride II
• Sankokushi

[i4200 VPU, YM2151+M6295 Sampler]

• Datoride (MT5620 Version)
• Gun Master
• Pururun
• Puzzli

[Unlabeled] Hardware [i4220 VPU, YMF278B Sampler]

• Mouse Shooter GoGo
• Bal Cube
• Datoride (YMF Version)
• Bang Bang Ball
• Battle Bubble v2.0

"Human" Hardware [i4220 VPU, Z80 Audio CPU, YM2610 Sampler]

• Blazing Tornado
• Grand Striker 2

VG330/VG340/VG410 Hardware [i4300 VPU, YM2413+M6295 Sampler]

• Mahjong Doukyuusei
• Mahjong Doukyuusei Special
• Mouja
• Mahjong Gakuensai
• Mahjong Gakusensai 2

VG2200 Hardware [i4300 VPU, Z86E02 Audio CPU, YM2413+M6295 Sampler]

• Puzzlet
• Metabee Shot

Special Mentions
Technically the Technosoft release "Hyper Duel" and "Magical Cat Adventure" are Metro hardware As is "Rabbit" by EA and "Tokimeki Mahjong Paradise" by Media/Sonet despite none of these games carrying the "Metro" label on the hardware anywhere.

 

[AlxUnderBase]

As a fan of Puzzle games I've always loved the Metro hardware.
There are a few generations of this hardware, each with slightly different audio CPU and an upgraded VPU (Video Processing Unit) making a truly universal multi impossible.

Since System16 doesn't list this hardware here are all the PCB variants and the games that they made

VG420/VG460 Hardware [i4100 VPU, uPD7810 Audio CPU, YM2413+M6295 Sampler]

• Last Fortress - Toride (VG420 Version)
• PangPom's
• Sky Alert
• Last Fortress - Toride (VG460 Version)
• Lady Killer
• Karate Tournament

MT5260 Hardware [i4100 or i4220 VPU, uPD7810 Audio CPU, YM2413+M6295 or YM2151+M6295 Sampler]

• Poitto!
• Dharma Doujou
• Torride II
• Datoride (MT5620 Version)
• Gun Master
• Pururun
• Puzzli
• Sankokushi

[Unlabeled] Hardware [i4220 VPU, YMF278B Sampler]

• Mouse Shooter GoGo
• Bal Cube
• Datoride (YMF Version)
• Bang Bang Ball
• Battle Bubble v2.0

"Human" Hardware [i4220 VPU, Z80 Audio CPU, YM2610 Sampler]

• Blazing Tornado
• Grand Striker 2

VG330/VG340/VG410 Hardware [i4300 VPU, YM2413+M6295 Sampler]

• Mahjong Doukyuusei
• Mahjong Doukyuusei Special
• Mouja
• Mahjong Gakuensai
• Mahjong Gakusensai 2

VG2200 Hardware [i4300 VPU, Z86E02 Audio CPU, YM2413+M6295 Sampler]

• Puzzlet
• Metabee Shot

Mouja is great puzzle . Its one of the latest games ive bought in 2024

 

[Mageta the Lion]

How high is the chance that the Imagetek I4220 and the YM2413 are backwards compatible? Was backwards compatibility a thing in the 90s?
(My googlefu fails me and a search for "Imagetek I4220" datasheet only provided links to MAME)

 

[XtraSmiley]

I have a Puzzli if that helps in anyway.

 

[twistedsymphony]

How high is the chance that the Imagetek I4220 and the YM2413 are backwards compatible? Was backwards compatibility a thing in the 90s?
(My googlefu fails me and a search for "Imagetek I4220" datasheet only provided links to MAME)

yeah I've yet to find one iota of data on the Imagetek chips outside of MAME.

based on the driver the i4220 seems like it could potentially run i4100 stuff. they're definitely pin compatible as the different chips were fitted to the same PCB for the differet games.

YM2413 is not cross compatible with the YM2151... however the PCBs VG420, VG460 and MTR5260 all have footprints on the PCB for both chips. So theoretically you could populate both of them and work out some circuit to switch between them.

that's not easy, and an equally complex issue is the MTR5260 used different 68K speed variants. there are 5 crystals on this PCB and nearly every game has a different clock configuration. So despite there being 8 or so games on this hardware, between the VPU, the audio, the clock speed configs, damn near every game is a unique configuration

The addressing logic on these is also tricky as they used a surface mount CPLD rather than a socketed PAL, and that's the key thing that needs to be changed to enable conversions

Are conversions possible? yes with a TON of work. Is a multi on that board variant possible? Theoretically but would be a real Frankenstein to make happen.

 

[ForestOfDreams]

Ok, which of you fellows bought the Toride on eBay i was trying to low-ball the seller on

Why is sincere supply always sincerely overpriced.
The only one I am seeing on the ebay.

 

[twistedsymphony]

Update:
I received the Pang Pom's board in today.
Verified that it runs well
Dumped the ROMs and confirmed they matched existing MAME dumps.
Scrubbed with IPA to clean off the mountains of sticky flux all over this board for some reason
Looking over the board closely I don't see any differences with my other VG420 boards.

Socketed the A21 and A23 PLDs and did brute force dumps

Analyzing the PLD dumps they're pretty much what I expected.
I tested my hand-crafted A21 Pang Pom's GAL and it works perfectly

So my understanding of the PAL logic seems to be completely correct

I removed the PLDs from the pang Pom board and install them on my non-working conversion, and it boots and plays!

So this leads me to believe that either my external remapping logic is incorrect, or the hardware I'm using isn't fast enough
At least I know it's not something more complicated!

 

[Darksoft]

Fantastic progress! My gust tell me it's the Logic, sometimes missing a small AND in one equation can change everything. Is the PAL maybe registered?

 

[twistedsymphony]

So there are 4 PLDs on these Metro VG420 and VG460 PCB
A21, A22, A23, and A24

A22 and A24 are identical across all games,
A21 and A23 are unique per game

A24 is sound related, it's very simple, only about 5 pins, used, but it is registered
A22 is interesting as it's used as a clock divider. pin 1 is connected to the 24MHz Xtal and one of the outputs is the 12MHz that drive the main CPU clock
Interesting but irrelevant to conversions or multi use.

A21 handles address decoding for ROMs, RAMs, VPU, as well as DTACK and VPA on main CPU

A23 handles address decoding for inputs, dips, coin counters, coin lockouts, as well as sound IRQ

None of these PLDs can be brute forced, A22 and A24 are registered and all of them use latching outputs

I have managed to hand-craft a replacement for A21. I have versions of this for all games on VG420 and VG460, I've only tested last fortress and pangpoms, and both work. I've been unable to test the VG460 version because my programmer doesn't seem to to want to program the GAL22V10 that is used for A21 on those boards

A23 I have all of the logic worked out and could easily hand craft replacements BUT I don't know how to get WinCUPL to compile with latching outputs, it gives me some errors that don't make sense and has stonewalled me.

if you're interested the specific error is:

The variable used as an input was previously assigned to an output that is neither bidirectional nor feeds back into the input array.

the problem is that the variable in question was never assigned to an output. Information on WinCUPL is very hard to come by so if anyone has advice on this I'd love to hear it!

 

[nem]

Information on WinCUPL is very hard to come by so if anyone has advice on this I'd love to hear it!

@Fluffy might know?

 

[ForestOfDreams]

Is it possible it defaults to output and must be unassigned?

 

[Fluffy]

WinCUPL is a horrible piece of software, and error messages are often misleading. It is sometimes hard to tell if an error comes from the language, or if it comes from the code that fits the design to the device. Without knowing the code it is hard to tell.

 

[twistedsymphony]

WinCUPL is a horrible piece of software, and error messages are often misleading. It is sometimes hard to tell if an error comes from the language, or if it comes from the code that fits the design to the device. Without knowing the code it is hard to tell.

aint that the truth!

My suspicion is that it's not really made for GALs it's made for Atmel's series of PLDs and happens to work for GALs, so once you get into the more unique features of the chip beyond simple logic it starts having issues.

Lattice's official software is ispLEVER but they want a few hundred bucks for a license and who knows if it would actually solve the problems.