Friday, November 29, 2013


I have successfully converted METAL SLUG 6 which works great on MAME but shows black screen on Real Naomi. I will start finding out why and release it ASAP.

I have also found that the first Atommiswave games had almost or no protection. The conversion process was "quite simple". The problem I'm facing now and that's the reason for lower pace in releases is that I found out that the new games have LOTS of protections inserted in the code in order to avoid games from AW being ported to DC or Naomi.

To give one example:

In memory region 0x10000-20000, Atomiswave has a flash rom and Naomi a ROM, so the AW game will try to erase part of that flash rom, everytime we boot (which btw decreases the life of our flash) and write some values there. Then it will read back from that part of memory. If we read the same, then we are good, if it doesn't read the same because Naomi has a ROM there, then it will crash or go to endless loop.
Another trick is to try to send weird commands to the GDROM, which AW doesn't have. You follow me right? In a Naomi will make the whole DMA, PIO pointers go crazy but will be ignored by AW.
Another one is to try to write to the extra ram that the Naomi has. If we read back the same, then we have extra memory that shouldn't be there and it will crash.

To put in short, Sammy, Sega and SNK probably faced a problem of piracy and started putting anti-copy measures quite sofisticated. Conversion of games from AW to Naomi is already quite a challenge, but that it's now clear to me, problem are all those anti-copying/anti-porting measures.

Just in Metal Slug 6 I had to modify the code in 47 places!!!

Hopefully I'll release something very soon!


  1. Is there any chance of making the blood red on metal slug 6?
    It would be nice to fix this.

  2. Wow thats a fascinating read! Very interesting that there is Naomi specific code present ONLY to act as a trap. I wonder what other sorts of measures they added...

    On a side note, have you had the chance to look at the games currently not working on a Naomi 2? I am considering getting a Naomi 1 motherboard just for these releases...

  3. I wouldn't buy a Naomi 1. It will be fixed hoepfully ASAP.

    Measures there are a lot, ranging from trying to read from the CD, writing to areas of memory present in Naomi and not in AW or viceversa, reading the content of the BIOS and use it in some calculations to make sure that the right BIOS is there, etc.

  4. First I want to congratulate, I wonder if it happened more algume or if this game anyway
    graphical errors in Metal Slug 6, but the speed this perfect makaron'm using the emulator.