Arcade Collecting > Merit/JVL Touchscreen

Megatouch XL Reverse Engineering Discussion

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tandrews:
After speaking with some people. I am pulling as discussion of my work. Things are pretty hairy legally and I can't afford any trouble. Until I hear further, no more information will be published or discussed on my part.

obcd:
I used dosbox to reverse as it has a rather good buildin debugger.
It was an older version without the cd check and with the square protection dongle.

Had to alter the dosbox sources a bit as the memory window used to access the nvram was hardcoded for the emm driver.

I basically logged the password that was sent to unlock the dongle and wrote a small program that used it to unlock the real hardware dongle so that I could read it's protected contents.

Next step was adding some routines to dosbox to emulate the dongle behavour.

And I had to choose a different sound driver. It was in the dig.ini file if I remember well. Believe they used something like "Miles sound system" which now became freely available.

It works for 95%. some transitions in the games are not correct, probably due to the video hardware not being correct emulated.

tandrews:
[Removed for legal concerns]

obcd:
Once you got things worked out, you can use it on real hardware as well.
It's for instance possible to jump to a TSR interrupt routine when an io is read or written.
It might in theory be possible to emulate the security dongle like that, but it's difficult stuff.

I assume your key is the dallas button style which uses the one wire protocol.

I might still have the IO ports I figured out for the io card. Just let me know if you have any use for them.

tandrews:
I was attempting to do something with a TSR but yeah, its more difficult for sure.

I've invested too much time into fixing the fixup records to stop now. I have written code that can search for a given record and i can then patch the record. This will allow for easy loading from file.

I am generally pretty good at reversing stuff, but hardware based things I can be a bit weak with. Your kung-fu is definitely sharper than mine:P

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