Good old interrupts, how come we don't do it like that for drivers anymore
this post was submitted on 14 Jan 2024
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We still kinda do, just depends on the kernel you're using. On Windows any IRQL > 2 is pretty much instant like the bird
What I'd like to know is:
-
Do modern systems - say within the past 10 years - still operate in this way when a PS/2 keyboard is plugged in (yes, some motherboards still do have PS/2 ports, bizarrely)? Or have modern CPU architectures, microcode, and updates to the x86 instruction set removed it?
-
Does it still work this way when you plug a USB keyboard into a PS/2 port via an adapter (I'd imagine yes, but I don't actually know)
PS/2 still works the same as it always has. No changes there. It's not really possible to change how PS/2 operates because it wouldn't be backwards compatible with old keyboards or software.
Legacy stuff sticks around for a while and generally doesn't change, since it needs to retain backwards compatibility. Modern x86 processors also still have a "real mode" with 1MB RAM max, like what the 286 versions of DOS and Windows 3.0 used to use.
You can buy industrial PCs and motherboards today that not only have a PS/2 port, but also other legacy stuff like parallel and serial ports, ISA slots, etc. There's actually motherboards that have ISA, PCI, and PCIe all on the same board. There's 25+ year old machinery that's still in use and extremely expensive to replace, so it's not uncommon to have new computers with legacy connectors/ports in industrial environments.
I was surprised when I just bought a brand new workstation and it had PS/2 ports.
Apparently some enthusiasts still use PS/2 keyboards because they have slightly faster response times / lower latency, and better support for n-key rollover.
Enthusiast motherboards still have the ps/2 ports as well. Usually because the usb controller is the first thing to stop working when the bclk gets too high or you're going sub 0 cooling.
PS/2 keyboards are more likely to support n-key rollover, too (USB is maximum 6-key rollover by default).
PS/2 Port on its way to harass the CPU
Seems the CPU has become the bully these days:
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
Keyboard: E
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
CPU: hey keyboard do you have anything for me?
..
My grandpa always used to say that computers used to be way better before they became electrical.
Ah, yes the good ol days of punch cards, switch boards, mechanical operators and electron tubes, when will the youngins learn that their fancy transistors are for pussies
Personally I inscribe all of my code into binary on a fired clay tablet and store it in a cave for archival purposes
No I meant the real computers
Low level accountants in the early 20th century.
No binary monstrosity could ever replace just doing it in your head.
I always appreciated Dunes idea of a mentat, basically an accountant trained from birth and juiced up on brain steroids to have equal computing ability to a high level AI. Usually when I think of the way human conciousness may evolve and trancend its current capabilities my mind goes right to the psychadellic-bro conciousness expansion and non-localized astral projection stuff, its interesting to consider there are other potential paths to augmenting human conciousness and what other boundaries could be pushed.
I don't get it...
Modern USB keyboards need to be asked what's being pressed by the CPU multiple times a second, but old PS/2 keyboards will actually interrupt the CPU to send the key press command
Oh, didn't actually know what's being done behind the scene...
Why is this relevant to Linux only?
It's not
Hm... then why is it posted in a Linux comm?
It's kind of a tradition among the r*ddit refugees from s*bs like linuxmemes and linuxmasterrace. Posting things that aren't strictly linux-related, but would still be appreciated in general by computer nerds.
Ah, didn't know that 👍.
Because it's funny, there's nothing that you don't already know.
assembly flashbacks
thanks for that KeyboardInterrupt