ROM dumping protection

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stunstall

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Anyone here able to answer some questions? Thanks in advance.

1. I've always wondered how ROMs are dumped to files so that they can (eventually) be emulated in MAME. Is there any "off-the-shelf" kit that does this and if so, what is it? Is it straightforward to use or do you have to get inventive with it? Are there any books or training courses? (Not that I have any ROMs, I'm just interested in this)

2. How is hardware protection (like Atari Pit-Fighter's SLAPSTIC) cracked? Yes, a niche question I know. I'm wondering if there are unprotected boards "in the wild" that can be used as comparisons to the encrypted boards to break the XOR tables used for security. I've read this: https://aarongiles.com/old/slapstic/ but it tells me how it works, not how he found out how it works. Note: I'm not specifically asking for Pit Fighter or Atari hardware, just hardware based encryption in general - what techniques are used to defeat it?

Any information would be most welcome - as I said, I'm not going to be dumping any ROMs, I just have an interest in this.

Thanks,

Scott
 
ColinD

ColinD

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Many Roms, Eproms and other kinds of devices can be read out using an eprom programmer, either directly or with the appropriate adaptor.


Some devices are locked such as micro controllers which contain code but can sometimes be tricked or exploited (Trojan). Sometimes they will open up a chip and take a picture and read the 0's and 1's out.... or do something that then allows you to read the data out. It's called decapping.

There are also PAL and GAL chips which are used in games, these are programmable logic devices and

you will often see some dumps of these too.

Hardware protection is another matter entirely.... Google will offer up plenty of bedtime reading..... this could be as simple as scraping the markings off some chips or encapsulating something in resin and swapping a couple of data and address lines around....ranging right up to using some serious encryption technology.

ColinD2020-07-07 19:08:56
 
S

stunstall

Newbie
Credits
32CR
Thanks for your reply Colin, much appreciated.

So when you decap a chip you can physically see the bit patterns on some ROMs? I thought they would be VLSI at least and not even visible with a standard magnifying glass (a scientific one would be another matter) . Incredible!
 
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