Hector Martin

I guess I could also do USB HID emulation, or even hook a GameCube bot through the adapter

You can just emulate a Joy-Con via Bluetooth with any PC.

but can you do it with frame-perfect sync for $run_duration?

Good question. I think you may not get sync over BT.

my original ATMega328-based replay-bot design took input over USB; connected to my MBP, it _usually_ synced for a 1-hour Mario 64 100% run, but never synced 15-hour ABC files had to switch to SD card input for that to work

maybe my new Teensy setup would be able to sync long-term with USB input, since it has enough RAM for more cache, and it's fast enough to use interrupts (+ has interrupt prioritization), but I've stuck to the card setup for now

What OS? This sounds like a job for rt-sources. I've done things like peg all cores compiling while still keeping glitch-free 8ms latency realtime audio synthesis. Or you could add more buffering to the hardware, yeah.

the host machine was running macOS, and then for some period was a Raspberry Pi 3 running Raspbian also tried to hook an RPi3 GPIO pin directly to the N64 (mapping the IO into userspace from /dev/mem), and managed to sync for a few seconds before being foiled by the scheduler