Initial testing of Retrode Virtual Boy adapter

When Matthias posted the news that he was working on an adapter for Atari 2600 carts for the Retrode, it made me think of something I had read years ago about Nintendo’s Virtual Boy cartridges (which I mentioned in the comments on the news post). It was a text file that documented how to connect a Virtual Boy cart to a Mega Drive copier. This was possible as they both use the same ROM (albeit in a different form factor). I never got round to trying it on any of my Mega Drive copiers, so I thought I would give it a try with my Retrode.

I will do a proper write up when I have more time. Here is a quick bit of info on what I did:

  1. Got a donor Mega Drive cart and Virtual Boy cart to try and read.

  2. Removed a PCMCIA slot from an old laptop.

  3. Extracted the pins from the slot (unfortunately the Virtual Boy cart doesn’t use a standard pitch connector).

  4. Tested the fit of the pins in the cart, seemed to be okay.

  5. Undressed both carts.

  6. Soldered wires to the PCMCIA slot pins.

  7. De-soldered the ROM chip from the Mega Drive cart PCB.

  8. Soldered the wire/pin combo leads to the Mega Drive PCB in place of the ROM chip.

  9. Joined the relevant wires from the Mega Drive PCB to the Virtual Boy cart as per the details in the text file.

I plugged the Retrode in to my computer and altered the Mega Drive file extension to be .vb, saved the config file and plugged the mess of a cart in. It showed up a file that was 6.12 MB which was obviously wrong as Mario’s Tennis is a 4mb cart (should show up as 512 KB). I tried it in an emulator anyway, but it didn’t boot, it just showed the error ‘Invalid PC - 00000000’.

I had a look at the file in a Hex editor and compared it to a known good dump of Mario’s Tennis, but couldn’t find anything that was visible in the good dump of the game.

I haven’t given up, I will re-check the connections are all going to the right place, and try again. If that fails, I will probably solder the wires directly to the Virtual Boy cart, to remove the possibility of poor contact between the pins and the connector. If I still get the same resulting file, I will have to get the old Mega Drive copier out and try it in that, to see if the text file information is correct.

I leave you with a photo of the mess in the Retrode.

Edit: Read part two, where I manage to get it working!

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