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Sega System 1 conversion - sanity check

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Flinnster View Drop Down
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    Posted: 11 Oct 2018 at 6:35pm
Hi,

I wonder if anyone here can help me with a Sega System 1 conversion board?

It's a Pitfall II, and I'm trying to convert it to a Wonderboy without altering the original board.
(I'm keeping the original Pitfall II roms so it can be reverted back if needed - even though some have rubbish labels currently).



I've managed to get a rom dump of another Pitfall II conversion board, so I was planning on
doing a direct copy of the ROMs on that, for the new ROMs on this board.
However, I've hit a snag. The CPU Rom data on that board doesn't run on this one.

So I ran RomIdent.. and it coudn't identify the first 2 CPU rom images. Only the third!
(All the graphics and audio ones were fine too).
So am I hitting encrypted code here?

The Pitfall II I'm running here (and trying to convert) has the label 834-5627-10.
It also has a main CPU daughterboard, which underneath has a PAL.
Looking further into the Pitfall2 CPU ROMs (6456A / 6457A / 6458A) they are indeed the encrypted romset in mame.

The Pitfall II conversion PCB I've been looking to copy, is labelled 834-5627-13. It just has a plain
z80 in the main CPU socket (Well an NEC D780C) - and the Pitfall2 CPU roms appear to be unencrypted (6623 / 6624 / 6625).

Most recently, CnP supplied me with a photo of his conversion PCB, which is also an 834-5627-10 labelled Pitfall2 like mine, running Wonderboy.

Like the other conversion PCB I've seen, he doesn't have the daughterboard, so I suspect that's been removed and swapped with a standard z80a.
Although his chip appears to be labelled D315-5177 - which gives me a hint as to which romset will be on his first two CPU roms.



I guess it's not possible to get NEC D315-5177 chips. Or 315-5135, 315-5178 to match the other Rom sets that are in mame?

MY question is whether it's possible to swap out the main CPU with any other standard 4mhz z80a, or an NEC D780C as used for the audio,
and then just run standard Wonderboy 315-5177 CPU roms?
Or even better, is there a version of the Wonderboy romset that runs on the Pal protected stock pitfall 2 z80 daughterboard?
(I doubt that, but you never know!).






Edited by Flinnster - 11 Oct 2018 at 6:39pm

Wanted: Outrun DLX cab, Rainbow Islands, Rolling Thunder, Original Wonderboy PCBs.
- Parts needed: Naomi wheels, coin mech metal clip for Dino King Door
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Asure View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Asure Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2018 at 8:20pm
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I've managed to get a rom dump of another Pitfall II conversion board, so I was planning on 
doing a direct copy of the ROMs on that, for the new ROMs on this board.
However, I've hit a snag. The CPU Rom data on that board doesn't run on this one.

So I ran RomIdent.. and it coudn't identify the first 2 CPU rom images. Only the third!
(All the graphics and audio ones were fine too).
So am I hitting encrypted code here?

This sounds like an undumped revision not currently in Mame. If possible, could you send me a copy of the roms by pm, so we can possibly add it one day? What were the rom labels/names on this copy you could not match up in romident?

I have been wanting to meddle with sys1 for some time, i have too many choplifter boots that i want to run WBML of WB on, but i never got around to doing it. I guess you could always try to run an unencrypted z80 with unencrypted code. (From one of the many wonderboy bootlegs.)
I would not play around with an original Pitfall 2 board, it's expensive these days. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ace` Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2018 at 8:29pm
Sounds like you need to remove the daughter pcb and put in a standard z80 or use encrypted roms. The 'undumped' roms aren't in mame as they're recent(ish) decrypted / hacked roms made to run on Pitfall II pcbs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote caius Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2018 at 8:56pm
Your Pitfall II runs encrypted code, the small daughterboard is a replacement of the custom CPU originally marked '315-5093'.
So all you need is to use a regular Z80 and an unencrypted ROM set but I warn you that all the unencrypted Wonder Boy ROM set in MAME are not good for your conversion.I know someone has prepared proper code but it seems it's not of public domain.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GadgetFreak Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2018 at 12:56am
I did a full decryption of the 315-5177 Wonderboy as I kept seeing complaints about the unencrypted prototype version. I also did the System 2 315-5177 as this is the one I needed to convert my Choplifter pcb.
They are in my patcher already but I haven't finished up the docs yet as have been too busy with other stuff. Drop me a PM and I can probably sort you out.
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