My keyboard uses PS/2 and although I do have a PS/2 to USB adapter, i prefer using my computers PS/2 port because it means one more USB port can be used for something else.
30+ years old and it runs flawlessly.
Isn’t almost any keyboard able to last that long?
I make sure any motherboard I buy has at least 8 USB ports, so I know I’ll have enough. It does make sense to use the PS/2 port if you have the peripherals. What advantage does USB have over it anyway?
Isn’t almost any keyboard able to last that long?
In theory, yes. In reality… not so much. Bluetooth keyboards are a joke for longevity, and a lot of wired keyboards these days just have piss poor build quality.
I don’t think PS/2 inherently has major advantages over USB but as someone who uses a small PC with few USB ports, I appreciate having a PS/2 port available.
I go through a cheap Logitech keyboard just about once every three years. I replace them when a a couple of keys stop working or when the nubs wear off of the center keys and can no longer blindly find where my hands go.
Usb keyboards can have n-key rollover which let’s you press more buttons simultaneously, whereas PS2 has a hard limit of like 5 or so
Refer to below comment
It’s actually the other way around. Check out Ben Eater’s awesome videos for technical details.
TLDR: PS/2 sends separate key up and key down events, sequentially - like - - - - each in separate message, allowing for theoretically infinite rollover (excluding certain edge-cases). USB, on the other hand, polls only for keys being pressed at the moment. By default, the keyboard responds with a 8-byte message, with 1 byte being the bitmask for 8 modifier keys (4 on each side), a spacer, and 6 bytes/slots for identifiers of keys being held down. If one identifier is present in one response but is missing or replaced in next one, the system assumes a key-up event. It is possible by USB spec to negotiate connection in such a way that the keyboard responds with a bitmask for every single key it has. But this is not well supported by things like BIOS and KVM’s, so very few keyboard manufacturers bother implementing it. Most keyboarrds advertising NKRO are actually only capable of doing so via the PS/2 adapter.
I’ve often thought this about older or less generally useful ports, but then it just keeps coming back to the fact that, if I had the same number of spare ports, plus one more USB that I useD for this keyboard instead of a dedicated PS2 or an old USB 2, I’d be in the same situation but with at least one more useful and fast USB that maybe I might for some reason want to use without my wired keyboard plugged in.
It makes sense in terms of cost, because the older more narrowly useful port is hopefully cheaper, but otherwise it’s just unnecessary and more limiting than the same overall number of ports where all of them are the most widely useful and fastest possible throughput.
