this post was submitted on 05 Oct 2024
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PS/2 things (lemmy.world)
submitted 1 month ago* (last edited 1 month ago) by [email protected] to c/[email protected]
 

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

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[–] [email protected] 1 points 1 month ago (1 children)
[–] [email protected] 1 points 1 month ago (1 children)
[–] [email protected] 2 points 1 month ago

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.

[–] [email protected] 1 points 1 month ago (1 children)

Does USB not use interrupts?

[–] [email protected] 1 points 1 month ago (1 children)
[–] [email protected] 1 points 1 month ago* (last edited 1 month ago)

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.

[–] [email protected] 1 points 1 month ago

Ah yes, the little old interrupt

[–] [email protected] 1 points 1 month ago

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 🤣

[–] [email protected] 1 points 1 month ago

Alright this has me giggling this morning