>Also wondering how much PS/2 vs USB matters. I had to get to grips with the USB spec when designing my USB scope [1]. Adherence to the USB spec itself doesn'

>Also wondering how much PS/2 vs USB matters. I had to get to grips with the USB spec when designing my USB scope [1]. Adherence to the USB spec itself doesn't necessarily create human-perceptible latency; HID frames can be transmitted every 1 ms and could be parsed in a negligible number of CPU cycles on an embedded machine with USB-OTG and no operating system. Like everything, the noticeable lag appears because the application-layer software is going through 15 layers of abstraction rather than talking directly to the input device, and this can become as complex and bloated as it wants. [1] https://espotek.com/labrador/ https://espotek.com/labrador/ (In case you become unable to resist your scope urge :P)