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.
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?
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.
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 had a Razer Blackwidow keyboard, lasted only like 6 years before the switches started dying. Or it got into a cult. Sometimes pressing k would type out kkk.
TLDR: PS/2 sends separate key up and key down events, sequentially - like #1 Down - #2 Down - #1 Up - #2 Up - 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.
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?
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.
You’re going blind because you rubbed the nubs off?
You look at the keyboard when you place your hands?
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 had a Razer Blackwidow keyboard, lasted only like 6 years before the switches started dying. Or it got into a cult. Sometimes pressing k would type out kkk.
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 soRefer to below comment
PS/2 does not have a key rollover limit
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
#1 Down-#2 Down-#1 Up-#2 Up- 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.Seems like I got my wires crossed, thanks for clarifying!
There are proper NKRO USB keyboards though. The packet sort of reminds me of a piano. Each key has a bit that says if it is pressed or not.
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.
Better than my old Razer Blackwidow. Did get almost a decade out of it, though.