Monday, May 7, 2018

Mostly PIC16C57

We were recently sent 8 "PIC16C57s" from:

  • High Seas Havoc (403/C013)
  • Wargods (U69, C020)
  • MACE (U96, C021)
  • Carnevil (U96, C022)
  • BioFreaks (C023)
  • Gauntlet Dark Legacy (C024)
  • Gauntlet (U37, C025)
  • Blitz 99 (U96, C026)

  • Here are the packages:

    First, note the upper left chip (BioFreaks):

    Hmm, that's not a PIC16C57 but rather a PIC16F57. We decapped a sample and its much finer technology than we've dealt with so far. This one's been shelved for now in lieu of easier targets.

    Next, note the lower left chip (High Seas Havoc (HSH)):

    The marking has been removed, but this is allegedly a PIC16C57. We popped it into a reader and it spit back a scrambled (protected) dump, so this was plausible.

    Here are most (Gauntlet Dark Legacy not shown) of the PIC16C57s after decapping and masking:

    These were dumped as done in previous posts. Here's Wargods close up:

    Next, you'll notice there are only 6 chips left of the original 8. In addition to BioFreaks, HSH was in fact not a PIC16C57. Additionally, its wires were a bit higher and got trimmed during decap:

    While its not a PIC16C57, it does look close, basically just with a smaller EPROM. It looks to be about 1/4 the size of PIC16C57 (2K), so lets say its probably 512 words. There are two members of the PIC16C5X family with 512 words: PIC16C54 and PIC16C55. PIC16C54 doesn't come in DIP28, so its probably PIC16C55.

    Fortunately we had a PIC16C55 on hand:

    Here's the identifying info on HSH:

    And here's a PIC16C55 sample:

    Odd...the die ID matches but the masks don't completely match.  After some discussion, we decided this was close enough to proceed. The main concern is that PIC16C55A has some more sophisticated protection that might be problematic if we tried a simple UV attack. However, HSH has a 1988 copyright, and the sample has a 1988 copyright as well. Additionally, we know that PIC16C57C was a big redesign over PIC16C57. So all evidence points that this really is a PIC16C55 despite the different masks.

    We secured a sample and applied a mask:

    Which after 15 minute or so of UV erasing had lost protection but retained the original data.

    Next we mended the broken wires. When we fixed similar chips in the past, we installed new wires. However, there are mostly wires intact, they just need some bridging. So instead of adding wires, we just carefully added conductive epoxy tracks to bridges them back together:

    Here the nail polish is being used to strengthen the wires from breaking as they get pushed around and also from having the epoxy short out against the edge of the die (see the lower left connection for example). This passed continuity and gave out the scrambled output we saw before decap.

    We then added additional masking to fully cover the EPROM;

    After 15 minutes of UV erasing we were able to retrieve the ROM.

    Finally, a few small updates on works in progress:

    • Taito C-Chip: we've dumped all samples we have except Operation Wolf (partial dump only). We have a spare chip in hand but we'd like to try a bit more to extract one of the existing decaps first
    • Contact mask ROMs (TGP + MCS48 such as Great Swordsman): general consensus is that the TGP captures are mostly acceptable, but the MCS48 captures are too noisy. We've briefly explored a few alternate capture techniques to improve accuracy, but haven't found something we are satisfied with yet
    • Altera FPGAs: we've been unable to identify the specific chip used for 79/80 based on samples we've procured. Reach out if you have interest in this / think you might have something to contribute
    • As the chips that can be trivially dumped dwindles, we are evaluating new analysis techniques. Some of these updates may be less frequent, but the write ups should be more involved

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    1. Nice job guys you are the best :)

    2. Waiting for some williams pinball pic too!

    3. Hello,

      Since you mentioned Great Swordsman chips, I made this offer to replace the damaged chips over on the MAMEWorld forms a while back.
      The offer still stands!

    4. Dedication m8 nice offer & thanks to the CAPS0ff Team too.

    5. 4:55 - In MAME, music and sound effects has stopped in Stage 1-5.
      The game was beaten by Yong, including AdMOS QS1000 sound emulation was based on real hardware as well.