Wow! That is convenient. Any idea on the projected print run and cost?
It is only a prototype, I don't plan to sell it at the moment.
Some people already suggested they wanted USB, so I think I'll add an additional FT232 chip for the next version (could be optional). The WiFi module is nice, because it has a programmable microcontroller (80 MHz RISC CPU) and flash (but not 512 MB ). First I wanted to add a SD card, too, but I don't need it, because all the programs for the Atari are so small, you can store a lot of them on the 8 MB WiFi module on-board flash, or at least on the external 1 MB flash, which I added just in case there are problems with the on-board flash or programming the integrated microcontroller.
Parts cost are less than EUR 40. The most expensive part is the big FPGA (about EUR 10). Could be replaced by a cheap CPLD (less than EUR 3), but it makes development much easier. For example it can store a stub for the menu program which is executed on reset, then it loads a second stage menu from the serial flash in the RAM, all without the microcontroller. With a CPLD there is not enough space to store a program or to implement the load from the serial flash to the RAM, so it would need some tricks, like a NOP slide and meanwhile the microcontroller fills the RAM, then switches to the menu program at the right moment. I could use a big parallel flash chip, but this makes routing more complicated (for my Kerberos board I used a 4 layer board).
Another thing which could be optimized are the voltage level translators. There are three 74lvc245 chips (8 bit voltage level translator), which cost EUR 0.50 per chip. With a CPLD with 5V tolerant IO pins (like the one I've used for my Kerberos cartridge, a XC9572) I don't need it. But maybe better to use at least one of the voltage shifters for the data bus, because the output of the CPLD would be only 3.3V.
Too bad Xilinx recently discontinued the XC9572. Of course, there are still lots of these chips to buy, but not good for a new project. Is there another cheap CPLD with 5V tolerant input pins, which is still manufactured?