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Nemesis1207
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Reged: 08/06/14
Posts: 11
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Undumped earlier Sega Hang-On revision
06/21/18 06:48 AM


I've been going through a stack of systems I've acquired over the years, testing and cataloguing everything properly. In the case of my arcade boards, many of these were bought as untested or broken for bargains, and went straight into storage for future projects. This is certainly the case for my Sega Hang-On board, which has literally been sitting in the original shipping box I got it in, on a shelf in my garage for the last four years. Here's the picture I had saved of it from the ebay auction:


I dug this out over the weekend, wired up a harness and plugged it in, and sure enough it wasn't working. Immediately on power-on, I was presented with a screen full of garbage, similar to this one:
https://2.bp.blogspot.com/-L0R-HMkl3BM/V...00/IMG_3470.JPG

Since this garbage appeared the very instant of power-on and changed each time, I assumed this was data from uninitialized memory, and that this memory was supposed to be cleared by the CPU(s) shortly after boot but wasn't being, so I started looking at the CPU board. I found it odd that every EPROM on the system had a hand-written label. I decided to dump and verify the ROMs on the cpu board first before moving on any further. The dumps went well and were consistent, and the data looked good, but when I looked for the corresponding MAME roms, I discovered the dumps I'd made weren't in there. The EPROM labels for the program code on my board are as follows:
EPR-6838
EPR-6839
EPR-6848
EPR-6849
EPR-6850
EPR-6851
In the "hangon2" set I found four roms marked as "a" revisions with the same EPROM numbers, but the contents didn't match. Somewhat concerningly, that same set contained name matches for EPR-6838 and EPR-6839 without an "a", but mine still contained a different code revision. I went ahead and did a dump of all ROMs on each board. Here are the board pics:
http://nemesis.exodusemulator.com/Arcade/HangOnDump/IMG_0741.JPG
http://nemesis.exodusemulator.com/Arcade/HangOnDump/IMG_0742.JPG
http://nemesis.exodusemulator.com/Arcade/HangOnDump/IMG_0744.JPG
http://nemesis.exodusemulator.com/Arcade/HangOnDump/IMG_0747.JPG
http://nemesis.exodusemulator.com/Arcade/HangOnDump/IMG_0750.JPG
The problem with this game is actually visible if you look closely at the CPU board. See if you can spot it, it took me half an hour.

Only six of the dumps from these boards are different from the base "hangon" set, the ones that contain the code for the primary and secondary CPUs. I found it interesting though that one EPROM was labelled as EPR-A6844. The contents of this ROM are a binary match for the existing EPR-6844 dump, so I'm not sure why this one EPROM is marked as an 'A' revision. Here's a link to the "upgrade" rom set, which I've informally labelled "hangon3". I included the "EPR-A6844" dump too due to the different name, even though it matches an existing dump.
http://nemesis.exodusemulator.com/Arcade/HangOnDump/hangon3.zip

This set can load and run in MAME. I haven't looked for differences with the other sets, but I can verify this set of roms is for an upright version of Hang-On, not a ride-on version like the hangon2 set.


Adding this into mame is a bit unclear, as there's real confusion between this set and the existing hangon2 set. First of all, there's a clear and obvious error in the ROM naming for hangon2. In the current set, the rom names of epr-6838.ic63 and epr-6839.ic51 are wrong, as the ROM numbers have been swapped for those IC positions. See the following image, taken by the guy who originally submitted the hangon2 roms to mame:
https://web.archive.org/web/20150224223839/http://homepage.ntlworld.com/cmonkey/IMAG0528.jpg

You can clearly see the chip in position IC51 is EPR-6838, and IC63 is EPR-6839. Somehow the dumps got mislabelled along the way. The original picture from that board along with my boardset confirms the correct order, so the roms should be renamed, which would also make the subcpu ROM name order consistent with the other hangon dumps. The current epr-6839.ic51 should become epr-6838.ic51, and epr-6838.ic63 should become epr-6839.ic63.

Even with that confusion cleared up though, it doesn't solve the problem that EPR-6838 and EPR-6839 are both labelled the same on my board and this one, and yet they clearly contain different code. My boardset doesn't have original labels though, so it's possible that it should have some kind of revision letter, but the guy who wrote them didn't bother to add them. Confusingly, both boards have "rev A" on them though. It does appear my board has had a ROM change, as those EPROM labels are too clean and white to have been on this board since it was made. They should have at least turned yellow like the board stickers, so it's likely someone copied these EPROMs from another system. If those were marked with an "A" or the like though, surely he would have copied that when writing the labels? Why would he have written EPR-A6844 on one of the other chips if he wasn't copying revision letters? But at the same time, why is EPR-A6844 a binary match for the EPR-6844 rom dump in other sets, which aren't labelled with an "A"? And why go to all the effort of copying the EPROMs at all? Every chip is labelled with a new label, and the datecodes on plenty of them are well into 1986, which is well after Hang On was first released in 1985. Why then do they contain an earlier revision of the game than has previously been found? Wouldn't this dump have been discovered by now if it was being sent into arcades for two years? If the EPROMs are from a later system, you'd think this is a conversion, but why then is the board marked with an original Hang-On sticker?

It's all very confusing. To add some more confusion, there's also the fact that the (speculative) ROM names for the hangon2 main CPU code are also EPR-6848, EPR-6849, EPR-6850, and EPR-6851, allbeit with an "A" suffix as the board was marked revision A. The main CPU code is definitely different between the upright and ride-on versions though, so why would they use the same ROM numbers? That board had black labels with no writing on the main CPU roms though, so the ROM numbers were unknown. It seems likely the ride-on ROM names for the hangon2 set are guessed wrong, and should actually come later (IE, EPR-6852+). The sub-CPU sticker was genuine though, and its contents are different than mine. I believe, but can't confirm, that those ROM names actually came from the 420-5244 Hang-On manual for the ride-on version (IE, this one: https://www.ebay.ca/itm/162773340773), in which case, we might have the rather horrifying case of Sega using the exact same EPROM number for what amounts to two totally separate "branches" of this code for two distinct cabinets with separate code requirements, the upright and ride-on versions of Hang-On.

So, maybe this new set is the original revision of the upright hang-on, or maybe it's revision A, or maybe it's something else entirely. No idea, I give up. All I know is, the EPROM names here are really screwy.

At any rate, enjoy the new dump. Oh, and the board is up and running now. Somehow the guy who had it last managed to insert the secondary CPU the wrong way around. I spun it back the right way, and the board booted and ran perfectly.







Entire thread
Subject Posted by Posted on
* Undumped earlier Sega Hang-On revision Nemesis1207 06/21/18 06:48 AM
. * Re: Undumped earlier Sega Hang-On revision Haze  06/21/18 02:11 PM
. * Re: Undumped earlier Sega Hang-On revision gregf  06/21/18 02:51 PM
. * Re: Undumped earlier Sega Hang-On revision Nemesis1207  06/22/18 02:08 AM
. * Re: Undumped earlier Sega Hang-On revision Haze  06/23/18 06:26 PM
. * Re: Undumped earlier Sega Hang-On revision Nemesis1207  06/25/18 05:42 AM
. * Re: Undumped earlier Sega Hang-On revision Hammy  06/27/18 03:27 PM
. * Re: Undumped earlier Sega Hang-On revision Nemesis1207  06/27/18 04:45 PM
. * Re: Undumped earlier Sega Hang-On revision Hammy  06/28/18 12:09 AM
. * Re: Undumped earlier Sega Hang-On revision jonwil  06/25/18 02:16 PM
. * Re: Undumped earlier Sega Hang-On revision Nemesis1207  06/27/18 01:55 AM
. * Re: Undumped earlier Sega Hang-On revision Haze  06/22/18 03:08 AM
. * Re: Undumped earlier Sega Hang-On revision *edit* gregf  06/21/18 01:13 PM

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