Well, here it is. After I had a brilliant idea followed by an epiphany about how to breadboard the cartridge slot, I started wiring it up. I had to install a voltage regulator to drop the USB 5V down to 3.3V that the NGPC cart could handle.
I didn’t wire up all the lines yet, but I was able to verify that reading works. I hoped this picture would show the result, but it’s a bit blurry. In the command-prompt window, you can see the first 8 bytes of the cart. In the other background window, you can see a ROM dump of the game (from elsewhere). The first 8 bytes match, which is a very good indication that it’s reading properly.
Next is to connect up all the address lines (which just takes time). Then I can test writing to a cart. Unfortunately, there’s not much to write to an official cart. I should be able to read/write the save-game areas of official carts until we have a writeable cart. Gerry is working on that, though.
Once I have a usable NGPC reader/writer, I will have to start learning VHDL. Then I can code up some routines for a MAX3000 so that the NGPC will think it’s an official SNK cartridge. Oh, what fun.
I suppose I can also fab some PCBs for this USB Pocket Linker. I’ve never done that before, but much of this is new to me. How hard can it be?