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Atari/Midway Vegas security chip BINs

ekorz

ekorz

Multi Boyz 4 Pi
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Maybe I put this in the wrong forum the other day, so I'll try here (slightly modified). My google-fu was weak... are the security chip bin's for Atari/Midway Vegas games public anywhere? I'd expected them to be in MAME source, but I couldn't find it. My first goal is to verify my Gauntlet Legacy PIC U37 I just dumped. Second goal would be to play around with other games the board can support, but I'm not even 100% sure if these chips are burn-able if I found a blank one.
 
I know a few people who sell them. At least one of them burns them himself I believe. Either way most of the dumps aren't shared. He wouldn't give me any of the files which I understand because it's a portion of the business he still runs.
 
Hm, maybe I'll just buy a blank one and see if I can burn it myself. I'm not sure what the difference is between this chip and a normal EPROM, except that the ones I see online don't look erase-able - no UV window. Otherwise it seems like you could write it once, verify, and be good. But I'm still new at this...

That still leaves me wondering how MAME does it
 
ekorz said:
Hm, maybe I'll just buy a blank one and see if I can burn it myself. I'm not sure what the difference is between this chip and a normal EPROM, except that the ones I see online don't look erase-able - no UV window. Otherwise it seems like you could write it once, verify, and be good. But I'm still new at this...

That still leaves me wondering how MAME does it
Click to expand...
if it's a security chip, that just answers an specific value(s) then the code in the program ROM will do some reading to a weird zone in memory, the processor will check for a specific answer. If this doesnt happen, then you get an error or game will hang or...
You just emulate the answer in MAME and that's it. You don't need to add an extra processor, which is what the pic is, add extra clock,etc. that would make it even slower.

Have a look here:
https://github.com/mamedev/mame/blob/master/src/mame/machine/midwayic.cpp#L710
 
A PIC is a self contained micro computer. It has ram, programmable rom memory, a CPU core and I/O peripherals(output pins, timer, serial port, etc) which it uses to interact with the external world once it's programmed.

So while it's programmed in a similar way as an EPROM, it certainly doesn't act like one as it runs.
 
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