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Apocalypse

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No mcu and any romboard hack released:
S18 : Moonwalker no mcu and any romboard patch! (testers welcome)

I guess this guide is useless now. ;)

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Hi guys,
finally got time to dig for my Moonwalker conversion on 171-5987 romboards, you know the "bad" ones with a SDIP64 custom chip on it. MCU is still needed.
Moonwalker uses a 171-5874 romboard.
This guide can also be used to convert other 171-5874 games on 171-5987 romboards by adapting some parts but I will focus on Moonwalker for now.

Conversion requires only one 74LS139, some wire and cutting or lifting legs from the sockets (it's up to you).

I've written all this from my (shitty) notes and probing on the converted romboard I made. I can't guarantee there's no typos or mistakes in this guide. If I have time I'll redo the conversion from scratch following this guide but for now you're doing this at your own risk.

1) ROM positions correspondence:

Of course layout being different, chips have different positions:

171-5874171-5987
A6A4
A5A6
-A5
-A7
B1B1
B2B2
B3B3
A1A1
A2A2
A3A3
B11B10
A11A10
B10B11
A10A11
B9B12
A9A12
B8B13
A8A13
A4B7
B4B6
B5B5
B6B4


Please note sockets A1/A2/A3 aren't used by Moonwalker.
Also the 171-5987 can support 4 program ROMs so has 2 extra sockets non existent on 171-5874.

This gives for Moonwalker:
A6 -> A4
A5 -> A6
B1 -> B1
B2 -> B2
B3 -> B3
B11 -> B10
A11 -> A10
B10 -> B11
A10 -> A11
B9 -> B12
A9 -> A12
B8 -> B13
A8 -> A13
A4 -> B7
B4 -> B6
B5 -> B5
B6 -> B4

2) Jumpers:
Jumper settings for Moonwalker on 171-5987

2/4/5/8/10/11
18/14/16/19
25/21/23/28
29/31/33/35/37/39/41/43
45/47/49/51
66/68/69/71

3) Isolating signals:


The 315-5436 on the 171-5987 romboards is in charge of banking sprites and tiles which means generating CE (chip enable) and higher address lines signals.
On 171-5874 higher address lines are directly connected to the CNx connectors. And inded chip selection for sprites and tiles is made by the 74LS139 using highest address lines.

CE lines of sprites ROMs (in sockets A10/A11/A12/A13/B10/B11/B12/B13) must be isolated by either leaving pins 22 sticking out of the sockets of cutting traces coming from the 315-5436 custom chip on the part side next to the chip:
- pin 52 = CE for sockets A10/B10
- pin 51 = CE for sockets A11/B11
- pin 50 = CE for sockets A12/B12
- pin 49 = CE for sockets A13/B13
Then pins 30 (A17) must also be isolated (custom chip 315-5436 pin 55) and then reconnected with a wire to CN2.b9

For tiles ROMs CE lines can be left as is, on 171-5874 it's generated from A18 (in fact /CE B1/B2/B3 = A18 and /CE A1/A2/A3 = /A18) by the 74LS139, but on 171-5987 custom chip is initialised with the signal being low and given we only have one bank of ROMs used by Moonwalker that does the trick.
However address lines A13/A14/A15/A16/A17 must be isolated, again by either lifting pins 28 (A13), 29 (A14), 3 (A15), 2 (A16), 30 (A17) and 22 (/CE) of sprites ROMs in sockets A1/A2/A3/B1/B2/B3 (remember Moonwalker doesn't use A1/A2/A3).
If you go for the cut route, just under CN4 you should have 12 vias arranged like this (2 rows of 6):
O O O O O O
O O O O O O
You must cut traces coming from the 315-5436 custom chip on the solder side. I've indicated with a X vias needed to be isolated (part side view):
X X O O O O
O X O X X O

And then rewire them as follow:
- pins 28 (A13) = CN1.a14 (top left X)
- pins 29 (A14) = CN1.b13 (second X top row)
- pins 3 (A15) = CN1.a21 (first X bottom row)
- pins 2 (A16) = CN1.b21 (second X bottom row)
- pins 30 (A17) = CN1.a22 (last X bottom row)

4) Generating sprites ROMs CE signals:

This is the last step, you must wire the 74LS139 like this:
- pin 1 = ground (pin 16 of any ROM)
- pin 2 = CN2.A10
- pin 3 = CN2.B10
- pin 4 = pin 22 of ROMs in sockets A10/B10
- pin 5 = pin 22 of ROMs in sockets A11/B11
- pin 6 = pin 22 of ROMs in sockets A12/B12
- pin 7 = pin 22 of ROMs in sockets A13/B13
- pin 8 = ground (pin 16 of any ROM)
- pin 16 = Vcc (pin 32 of any ROM)


You should now have a working Moonwalker.
 
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Apocalypse

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Of course by doing a proper program ROMs hack none of this is needed, it's a simple romswap with few jumpers to be moved.
But no one found motivation yet to work on it...
 

jassin000

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I know System18 has few good/quality games, really only three come to mind...
  • Moonwalker
  • Shadow Dancer
  • Alien Storm
However because we have decrypted ROMs available for these games and we can just swap out the 68000...
Would you ever consider making a multi? :D

I'd give Hammer Away a shot if I could easily do so (no way in hell I'm doing a conversion for it).
 

Apocalypse

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I know System18 has few good/quality games, really only three come to mind...
  • Moonwalker
  • Shadow Dancer
  • Alien Storm
However because we have decrypted ROMs available for these games and we can just swap out the 68000...
Would you ever consider making a multi? :D

I'd give Hammer Away a shot if I could easily do so (no way in hell I'm doing a conversion for it).
What?! You don't want key writing for that one? Good news is ALL games use a FD1094 module, so less messy than S16B with 3 different modules for main CPU plus a fourth one for sound CPU.
I do have a 100% hand soldered prototype on a piece of breadboard, main reasons I'm not communication too much about it is:
- Moonwalker requires a i87C51 (or equivalent) MCU for protection. It's the only game needing it but if left in place other games don't boot. I could add a wire to maintain the MCU in a reset state when not needed but it's messy (and I'm not sure any CPU/MCU is meant to be held in reset for very long times, I've repaired few boards in the past where the reset circuitry was faulty and always low and as a coincidence reset input of CPUs were fried, or maybe it's the other way round and the faulty input killed the reset circuit). An other solution would be patching code to completely get rid of the MCU.
- Hammer Away is 171-5987 (romboard) exclusive. The mutli obviously doesn't have the required 315-5436 custom chip this romboard uses for sprites/tiles banking. One solution could be to patch writes to 0x3e000* (tiles) and 0x3e001* (sprites) in the code.
 

jassin000

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Well I'm interested in one, and yes if key writing/restoration for this is the way to go I'm all about it.
I figured key restoration on these wouldn't be possible because of MCU protections and the need to remove them.

Anyway yea, if the final price clocked in at about 300$ or less I would 100% buy one (that's 100$ for each of the three awesome games on the system and worth it)!
 

jepjepjep

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D.D. Crew is a great beat'em up too. Once you figure out that you can only hit one enemy out of the crowd (unlike the Final Fight style), the game really opens up. It's a lot of fun with that 90's cheesiness.
 

-Ace-

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Can a Laser Ghost be converted to Moonwalker?
 

Apocalypse

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Can a Laser Ghost be converted to Moonwalker?
Yes Laser Ghost, D.D. Crew, Desert Breaker and Clutch Hitter can all be converted to Moonwalker with this method.
Actually you should wait a bit (unless you desperately want to play Moonwalker), I'm preparing a patch, so far I'm down to a single wire mod:
Apocalypse said:
(For sprites ROMs) Then pins 30 (A17) must also be isolated (custom chip 315-5436 pin 55) and then reconnected with a wire to CN2.b9
 
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XtraSmiley

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@Apocalypse this is great and all, but you're time should be spent on the S18 multi, not conversions!

:P

Of course, it's your time, so I'm only joking, but I think more people would be better served if they bought the multi instead of spending money doing just one conversion.
 

sk8er000

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Really looking forward to convert my clutch hitter PCB to Moonwalker..

In that way I'll be able to patiently wait for a future multi :whistling:

As always thank you for your great project @Apocalypse :thumbsup: :thumbsup:
 

Apocalypse

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I do have a 100% hand soldered prototype on a piece of breadboard, main reasons I'm not communication too much about it is:
- Moonwalker requires a i87C51 (or equivalent) MCU for protection. It's the only game needing it but if left in place other games don't boot. I could add a wire to maintain the MCU in a reset state when not needed but it's messy (and I'm not sure any CPU/MCU is meant to be held in reset for very long times, I've repaired few boards in the past where the reset circuitry was faulty and always low and as a coincidence reset input of CPUs were fried, or maybe it's the other way round and the faulty input killed the reset circuit). An other solution would be patching code to completely get rid of the MCU.
- Hammer Away is 171-5987 (romboard) exclusive. The mutli obviously doesn't have the required 315-5436 custom chip this romboard uses for sprites/tiles banking. One solution could be to patch writes to 0x3e000* (tiles) and 0x3e001* (sprites) in the code.
Both issues fixed, sprite banking is indeed not needed for Hammer Away on 171-5874 romboards (or multi ;) ).
 

jassin000

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MULTI!
So I take it you will at some point sell a System18 multi?
I'm expressing my interest in such a device NOW!
 

jassin000

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Maybe this is a strange question... But could the System16 multi be modified/reworked to support System18?
That way you could sell me the V1-S16 multi with a few additional pieces/wires/and instructions to make it work on S18?
 

Apocalypse

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Connectors are different (four 2×25p on S16B, two 2×30p and 2×25p for S18) so as connectors spacing.
 

jassin000

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Ah, I never actually looked/counted but I thought they both used the four 2x25 connectors.
Well if you ever consider a small production run keep me near the top of that list. :thumbup:
 
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