> I'm going to have to say that it's impossible, plain and simple. the

you're absolutely right about the NES being incompatible with an IDE
or SCSI bus. But that doesn't mean it's impossible to do.

Any modern FPGA (or even an average CPLD) can run at speeds exceeding
100MHz. The NES is what... max 4MHz? It's certainly possible to make
an IDE interface, with some buffer memory, that would appear to be a
normal cartridge, from the console's point of view. The FPGA would be
configured to retrieve a game from the HDD, buffer it (at least
partly) and then behave like a game cart. Using a 20GB 2.5 inch IPod
Hard drive (easily fits in a cart, with lots of room to spare), you
could fit tons of games, probably all games that exist (I don't have
any numbers handy, but I think there are no more than 1000 - 1200. A
quick calculation tells me that 1000 games could easily fit on a 10GB
drive)

I find this is a pretty good idea... when I get good at programming/
hacking my new NES, this is probably going to land on my 'to try' pile.

While we're at it... using the same FPGA interface, it isn't much
harder to include compactflash/usb drive/you-name-it support.