In todays edition of “stuff that I found in my storage” a PS/2 meme
Image transcription:
mov rax, rbx add rax, rcx HELLO IT’S THE KEYBOARD I HAVE AN IMPORTANT MESSAGE E
Alright this has me giggling this morning
Ah yes, the little old interrupt
Underrated meme
Help me understand pls?
Ps/2 keyboards used interrupt when transferring data, meaning instead of waiting for the cpu to get the data it is trying to send when it is free, it will just interrupt what the cpu is currently doing and tell it to process what the keyboard is sending.
Does USB not use interrupts?
No. It’s polling based
Actually it’s both, there’s polling with a timeout interrupt if an incoming urb hasn’t been processed quickly.
https://crlab.ece.ucr.edu/usbgps/ohci_uhci.html
This way you can take them in batches at regular intervals.
What bothers me the most here is that those are 64 bit instructions, which did not exist when PS/2 was a Thing. But I still chuckled, nice work.
Back then our registers were 32 bits wide, and we liked it 🤣
