SOLVED: Super Hang On (mini ride on) bad road signs

Yeah, the FD1089B key is available, it's how MAME decrypts it to be played.

So to decrypt it to work on a regular 68000 the key is still needed, but that's not all.

The encrypted CPU uses the key in different ways if the CPU is reading an instruction (opcode) or data. When Sega created the ROMs they have a mask that specifies what each byte of the ROM should be encoded as (opcode or data).

To create a decrypted version of these ROMs that would run on a regular CPU you need the same mask to know which of the two decryption processes to follow. You can use MAME to help make this mask - because you could log what bytes are read as opcodes and what bytes are used as data as you play the game. But to be 100% - you have to make sure every possible instruction path is followed. Otherwise you have a chance of ending up with an incorrect mask that would crash the game if it read an instruction that had been decrypted as data.

Because knowing if the game has ran every instruction path is difficult/effectively impossible, you have to finish up the mask by hand by examining the disassembly and checking if it could ever branch to a data segment.

I might be making this sound more complex than it is - for someone familiar with 68000 code and MAME it might be 2-3 hours work. (But still - pain in the ass)
 
Interesting - so all the information I would need is already available. Just someone to do it...I learned MIPS assembly back in college 🙃 though I'm not sure I'm ready to pick up the job. It would be interesting to do though...I'll have to learn more about debugging MAME I suppose if I want to make a legitimate pass at it.
 
Well - for anyone wondering. Problem solved. Game is much more playable. May not be on the OG rom set, but good enough for now.
 

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Great job finding a fix! I think I've run into a very similar if not the same issue, and noticed that strangely if I'm in the diag test menu it shows checks for vibration even though that's only on the upright?

It's like the road is the correct game version, but the signs are not. Will try loading the LE roms, have never done this sort of thing before so wish me luck!
 

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Yeah, that would make sense. I'll have to check my diagnostics. From what I recall reading up on, the limited edition was supposed to be an easier ROM set for the upright units. Which might explain the vibration setting.

I'm glad my saga was helpful to solve the problem for another owner!
 
Thank you so much for sharing your findings! I've been on this site for 20 years and still continue to find posts showing great work done by people here with great problem solving skills on these old relics!

I once noticed with my TRON that my graphics looked slightly different from others' games that I'd played. Crosshatch pattern on grid bugs screen was missing. Like your situation, it was playable, but the issue was very annoying to me. Thanks to people here at KLOV, I learned that someone had turned the monitor brightness down just enough to change the graphics 😑
 
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