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Tecmo SilkWorm to Gemini Wing ?

JoyAgain

JoyAgain

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Is it possible to convert a Tecmo Silworm To Gemini Wing ?
I ask you if anyone has done this before, before starting this conversion uselessly.
Thanks.
 
stj said:
it wont just be a romswap if that's what your asking.
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Need the patched code ?
There are no protectors on my Silkworm pcb (z80 custom). Gemini Wings pcb also appears to be unprotected.
The PCB looks identical to Gemini Wings, but both cards have completely covered in the traces.
Physically different perhaps?
 
acording to mame there are differences in how the tilemaps/sprites are handled.
if you have both boards or decent photo's you may want to compare numbers on any programable logic or customs.
i'v not seen my silkworm board for years, but you spiked my interest now. :)
 
looking at the MAME driver the only difference is the memory map.
video ram, main ram, sprite ram and palette are in different locations

on most games this can be fixed with a PLD swap or custom PLD
you can potentially fix with patching, but given it's a RAM move it'd be A LOT of patching.
PLD swap is way cleaner and easier.
 
@JoyAgain - Did you ever try this? Your post got me interested and I picked up a Silk Worm for cheap and successfully converted it to Gemini Wing

It ended up only being a ROM swap for me, but my Silk Worm rom set that I dumped from the board does not 100% match MAME. My 5H and 5S roms are different and trying to run plain Silk Worm in MAME with those roms swapped yields non-functional results. I will be submitting my ROMs to MAMEDev to see if they hae any thoughts. I need to try to run them as Gemini Wing (that will be a tomorrow thing, at this point).

After googling around, it looks like there may be various revisions to the board set (particularly the bottom board, with some boards having a daughter card full of TTL logic chips rather than the consolidated Mitsubishi chip that's in corner by the power connector), so I can't guarantee that this will work on boards with a different layout.

Here's how the Silk Road -> Gemini Wing conversion looks on my end. I'll post more pics (of the original rom set, etc.) when I get a chance:

tecmo_top.jpg



tecmo_bottom.jpg
 
Da quello che vedo, la tua scheda "Silk Worm" sembra una "Gemini Wing" modificata in fabbrica. Questo si può notare dal colore del PCB, che è bronzo e non verde menta come quelli standard della "Silk Worm". Un altro indizio è il chip Mitsubishi al posto della scheda logica, presente solo sui PCB della "Gemini Wing". È probabile che il tuo set "Silk Worm" sia stato modificato in fabbrica per funzionare sul PCB "Gemini Wing". Tuttavia, questo conferma che sarebbe sufficiente modificare il set di ROM per far funzionare il classico PCB verde menta della "Silk Worm".
 
JoyAgain said:
<From what I see, your "Silk Worm" tab looks like a factory-modified "Gemini Wing." This can be seen from the color of the PCB, which is bronze and not mint green like the standard ones of the "Silk Worm". Another clue is the Mitsubishi chip instead of the logic board, present only on the PCBs of the "Gemini Wing". It's likely that your "Silk Worm" set was modified in the factory to run on the "Gemini Wing" PCB. However, this confirms that it would be enough to modify the ROM set to make the classic mint green PCB of the "Silk Worm" work.>
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I agree, I think the reason this was a ROM swap is because it was a factory conversion, or perhaps a way for them to sell more Silk Work PCBs with inventory of Gemini Wing PCBs they had remaining.

Would be great to see this dumped and added to MAME! I'd suspect it has a memory map identical to Gemini Wing.

While theoretically true that Gemini Wing Code could be modified for Silk Worm hardware it's a lot easier for the company to change a few variables and recompile, than it is for us to modify all of the binaries to change the map.... still likely easier to swap PLDs
 
Would be cool to dual boot a gemini/silk worm & it sounds like it would work for both boards with a little work.
 
twistedsymphony said:
I agree, I think the reason this was a ROM swap is because it was a factory conversion, or perhaps a way for them to sell more Silk Work PCBs with inventory of Gemini Wing PCBs they had remaining.

Would be great to see this dumped and added to MAME! I'd suspect it has a memory map identical to Gemini Wing.

While theoretically true that Gemini Wing Code could be modified for Silk Worm hardware it's a lot easier for the company to change a few variables and recompile, than it is for us to modify all of the binaries to change the map.... still likely easier to swap PLDs
Click to expand...
That is what my thinking has evolved to as I checked more photos/auction listings. It looks like a lot of what I found and thought were true Gemini Wing boards are likely bootlegs (no Tecmo references) and what I ended up with was an actual Gemini Wing board running Silk Worm.

RepairGuy95 said:
Would be cool to dual boot a gemini/silk worm & it sounds like it would work for both boards with a little work.
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Possible... yes. A good idea.. ehhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh :D

Vertical vs. horizontal orientation, the bulk of the roms being 28-pin 27C512's meaning you'd have to use non-JEDEC 27C1000/HN27C301's with pins hanging out and a rats nest of wires to rig them up...

I think I'd just lean on the fact that Silk Worm is a kinda average game where Gemini Wing (particularly with 2 players) is a much more fun experience (but maybe that's just me and my opinion :P)
 
@twistedsymphony I'm still trying to figure out what the PLDs on these boards would be :dead:

There's a ton of TTL 74LS logic chips, so I'm thinking it has to come down to one of these chips:

MN50005XTA_59.2.jpg



M60002-0118P.jpg



But, according to Caius' work, they're just consolidated TTL logic so I'm even more at a loss as to the difference between dumped Silk Worm boards and Gemini WIng: https://caiusarcade.blogspot.com/2023/09/mitsubishi-mn50005xta-and-m60002-0118p.html

Maybe I missed a chip on the board, but nothing is popping out to me as a PLD.

I can confirm that renaming the Silk Worm roms that I dumped to match Gemini Wing and running in MAME does run Silk Worm without issue (sorry for my VERY dusty desk):
silkworm_as_gemini.jpg
 
yeah I was looking over pictures to see if I could figure this out myself. it might NOT actually use PLDs and instead have different PCB routing and/or different logic chips. you'd have to trace out the address lines from the CPU and then see where they go.
 
JoyAgain said:
it doesn't have a PLDs
Click to expand...
Do you want me to take a bunch of close up photos of my Silk Worm/Gemini Wing and assemble something so you can more easily check the TTL logic chips on my board vs. yours?

Given Tecmo's love of using paint on the PCB in this generation of hardware to obscure the traces, I wouldn't be surprised if the logic chips were identical but the traces were different.

I unfortunately don't have time to multi-meter everything and create schematics, but the photos won't be an issue. I think I have an old CLI program called autostitch that could assemble them together for me.
 
OK... so there probably was a better way to do this :dead: but the only way I could think of getting a semi-consistent zoom level for images was to rig up my microscope and use a 4-wheeled dolly with a piece of plywood across it and then a wooden stool on top of that to hold the PCB so I could just roll it around and take screen shots.

I was able to semi-automate the photo assembly, but it's not pretty. My RPi 4b that the microscope is hooked up to is just too slow to record video that was usable (that was my original plan).

Anyway, if anyone cares about the map of LS logic chips on a Gemini Wing Tecmo board, here it is: https://mega.nz/file/ltEgzBrb#BpbOMYl_WbCfq7qAj6-OlGSiuUp2HaXd11qrcEYtRVM

I had to hit some of the chips with alcohol to make their silk screens visible. Most of the ones that are dark brown/greenish that are semi-legible are LS08's

@JoyAgain Hopefully this is some help in seeing if the difference between your Silk Road board and this Gemini Wing board is LS logic chips or the traces we can't see.
 
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Pr3tty F1y said:
Anyway, if anyone cares about the map of LS logic chips on a Gemini Wing Tecmo board, here it is: https://mega.nz/file/ltEgzBrb#BpbOMYl_WbCfq7qAj6-OlGSiuUp2HaXd11qrcEYtRVM
Click to expand...
that's a bit overkill, but appreciated!

I don't see any programmable logic but changes are the 74LS138s or 74LS139s are responsible for the main address map decoding. you'd need to see how the higher level address lines of the CPU are routed and if they're routed to the inputs on these chips.
 
twistedsymphony said:
that's a bit overkill, but appreciated!

I don't see any programmable logic but changes are the 74LS138s or 74LS139s are responsible for the main address map decoding. you'd need to see how the higher level address lines of the CPU are routed and if they're routed to the inputs on these chips.
Click to expand...
Totally overkill :wacky:

But I already had everything setup when I went to record video that ended up being a blurry mess at like 4fps, so - in for a penny, in for a pound. I'll have to see if there is anything that I can tweak to make that possible to record at least semi-smooth 720p video on a RPi 4b as I am not planning on purchasing any high end camera equipment that would be able to capture the entire board in one fell swoop.

There definitely are no PLDs. I only imaged the LS logic chips as they're the only other easily modifiable potential variable aside from the traces. Unfortunately, these PCBs are painted and I just don't have it in me to create my own schematics with a multi-meter at this point.
 
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