Wow, this looks fantastic - I just ordered one for myself.
I have a question about the addressability of the flash memory from within a program...
Years ago, I had used Jerry DaSilva's TurboROM board in conjunction with AMD 29F040B DIP flash memory.
At the time, I had written a flash version of the "Ten no Koe" bank card, to copy the backup memory contents into the flash memory itself for longer-term archiving.
It worked fine, on a TurboGrafx-16, but it didn't work so well on the TurboDuo - I concluded that it was because of the power available from the cartridge bus being sufficient to read the flash, but insufficient to write into it. (Those boards didn't do download, thus the only power draw was the flash chip itself, which must have required a lot of juice.)
Since your version uses a TSOP chip (probably a more recent shrink), and there was a comment about lower current drain, I was curious as to whether this approach may work for your board.
So, I have a couple of questions:
1) Do you inhibit /WR from the PC Engine bus to the flash memory ? (ie. this would prevent it from being writable while in-circuit)
2) Roughly what vintage are the flash chips - 0.5um ? 0.35um ? (Not sure if they made this easy to determine). 5V-native chips are probably pretty old... also wondering the rated rewrite cycles ? I believe they were insanely huge numbers back then.
3) Is it possible to read from the flash memory via the USB ? If so, does your software already do this ?
