What useful permanent peripherals via the expansion port?

[Myask]

^^^boo. If we're gonna do that, bar/dotcode instead, be an e-Reader.

Would some kind of IRQ be of any use? Or is that too much easier to just build into the cartridge?

It's of some use; it lowers per-unit cart cost by putting it in the expander
You have A15 on the expansion connector, so you could practically just run traces A0-8 and R/W to EXP lines, and have the expansion device (the 16XDD) decode what ports do what.

Actually, that brings up a novel, but silly use of one EXP pin: giving A15 proper to the cartridge. This would also serve as a way to hard-require the device's installation for playing a game.

[FrankenGraphics]

bar/dotcode

Like this? Not to be confused with the Virtual Boy - but it will hurt your eyes all the same if you do

[Myask]

like the Barcode Boy or the GBA e-Reader…though I suspect having an insert+remove-style would be better for a home-console.

Magnetic strip reader! card-chip reader! Credit-card requiring home arcade games!


vvv Yeah, or that; forgot as-unfamiliar what the NES version was.

[lidnariq]

Or the Datach...

[tepples]

Except nowadays the e-Reader is so forgotten that people think it means an electronic device to display downloaded books.