Out of curiosity, what is the practical use of full N-key rollover? I can't think of many things that require me to press more than maybe five keys at a time.
Used to have these problems when we were children and playing fighting games with my brother with one keyboard or guitar hero clones that need you to press multiple buttons at the same time, that's the only use case I could think of. I don't know if there's any modern software that requires you to mash more than 2 or 3 buttons at the same time
Bit of a niche use-case, but I'd like to have it for using my laptop keyboard as a piano keyboard, for basically MIDI input (via VMPK or one of the DAWs with this feature built-in).
There's even certain combinations of just 4 keys, which I simply cannot play...
How about a fancy IBM keyboard? The Model F from 1981 features n-key rollover. Don't ask me why they needed it at the time though. It probably wasn't important as the Model M from a couple of years later dropped that feature.
Nothing to do with the interface. If your keyboard can only do 4 it means that the manufacturer has cheaped out on diodes and couldn't even be bothered to stagger the matrix enough to make you not notice.
I recall NKRO was the selling point on some of those keyboards, my old steel series mechanical will absolutely let you mash all the keys with a ps2 adapter.
USB: Many designs and revisions, none of them perfect
Nah, USB 3.2 Gen 2x2 SuperSpeed is the best! And it took me only 30 minutes of reading articles and wiki pages to get that information! althoughI’mnotsurewhatUSB4Gen3×1is,butit’sonlyx1socan’tbethatgood,right?
I know this is a shitpost, but what's interesting is that even though USB doesn't directly interrupt the CPU it's still faster. USB is able to get the entire packet sent before PS2 even sends one. It's very interesting. So if you ever see anyone unironically saying there is less latency call them out!
Are PS/2 ports still operating on hardware interrupts these days? I would expect these to be emulated as USB devices at this point, depending on whatever I/O chipset is in play.
The bit about USB asking the CPU is kinda true? My understanding is that it's a packet protocol of sorts, so it's really just writing post-it notes for each button press and leaves them on the CPU's whiteboard for later.