Why do we still have PS/2 ports on motherboards?

Most of my asrock boards have a com header, as do just about any server board I run across. Recent motherboard designs are all using a LPC "SoC" of sorts which support this and many other legacy things, whether or not they provide connections to those pins is up to the OEM.

They all have SMbus and similar for fans, temps, voltage etc stuff, so serial is never going to "die".
 
I have found that USB to Serial connectors with FTDI chips are great for compatibility and I have yet to find a system that cannot use them as if they are native, even old plasma cutters.
 
I miss parallel ports a little. Those were handy for interfacing random oddball stuff, e.g. Atari joysticks.
 
PS/2 ports stuck around for keyboard use due to full NKRO support and being interrupt-based vs. polled. It's a legitimately superior option for enthusiasts, which is why enthusiast boards keep it - and on top of that, it enumerates during the POST process much faster than USB does, as already mentioned.

And since people are mentioning RS-232 DE-9 serial ports in here, any serious bit of server/workstation equipment has at least one so that you can hook up a serial terminal (as every UNIX system and deriative thereof supports) and figure out what the heck is going on in the system if the graphics and USB adapters aren't doing their usual jobs.

Small wonder why UART serial headers can be found on just about anything embedded - it just works, without all of the cruft that USB brings. (And if you read the documentation on USBUHCI drivers for DOS, you'll quickly find out that USB is anything but universal at a low level, hence the UHCI/OHCI distinction. Those drivers don't work on OHCI, Power Macs can't use UHCI...)

Parallel ports, though? I admittedly don't have nearly as much use for those, since my printers of choice are networked and nothing else I have peripheral-wise really uses them. My Zip 100 drives are SCSI and USB, in the event that I need to mess around with a popular but obsoleted storage medium.

Perhaps I'd feel differently if I had that MPEG decoder some people plop onto their Amigas for multimedia playback on anything less than a Vampire board, or the joystick adapter that allows for 4-player support in certain titles (two on the built-in ports, two on the adapter).
 
About 6 weeks ago I finally sold my "old" PS/2 KVM off my test bench and bought a USB one. Prior to that, having a PS2 port on the motherboard was a must... even the USB adapter dongles didn't always pick up right on the KVM. Now... maybe not so much. But it's nice to have options. I have certainly worked on enough computers with USB keyboards that don't initialize fast enough to get into BIOS. Seems less of an issue now, but so many times I have been happy to have a real PS2 keyboard in the closet when I needed it.
 
I just bought a new X470 MSI mobo, low and behold it has a PS2 port, I was laughing my ass off lookin at it. I haven't seen PS2 keyboards since 1990's. Didn't even know the still sold them? this is nutz.
 
Motley said:
I just bought a new X470 MSI mobo, low and behold it has a PS2 port, I was laughing my ass off lookin at it. I haven't seen PS2 keyboards since 1990's. Didn't even know the still sold them? this is nutz.
Click to expand...

It isn't for new keyboard sales mostly. It's for the people who have ancient but awesome IBM buckling spring keyboards and will knife fight you if you tell them they can't connect it. That group has a heavy overlap with high end motherboard purchases, perhaps counter-intuitively.

There's another fringe group which will provide walls of text about N key rollover or some microsecond latency or similar.

Mostly it's us old people with lots of money, old keyboards which were awesome and still work, but we want MOAR COREZ.
 
It's interesting that the PS/2 port has long outlived the system that created it. I still remember how much of an inconvenience it was to adapt the ps2 to the normal AT port, which also had nothing wrong with it.

It actually shocks me that of all the changes IBM introduced with the PS/2 line, including the venerable Microchannel that was almost identical to modern PCI (not PCIe kiddies), that the simplest, stupidest change is the one that stuck--changing the keyboard connector to the little round ps2 from the slightly larger round at connector. Maybe it was because it matched the connector for the ps2 mouse, but that was another oddball in a time where plugging in a mouse into a serial port was like our modern day usb ports today--why the change?

Nevertheless, the legacy is still there and still alive for whatever reason. Personally, I have run into the bios issue with usb keyboards and they are laggy and a lot of times won't recognize until X happens, which bugs me to death (I want to ctrl-alt-del NOW, not when you tell me you're ready for it!). So I'm actually quite happy to see a ps2 port when I see one because I know reliability is just a plug away.

I have model Ms and almost exclusively type on them (for going on almost 30 years now), but a usb adapter doesn't bug me at all for these (typing with one now in fact), but a keyboard port that can't do the job is just a usb port to me. :D
 
Got me curious if I had a PS/2 port on my Gigabyte X470 and nope I dont have it
 
PS/2 ports are actually very useful for debug entry key combos, thanks to that hardware-level interrupt.

Modern Cisco servers lack the PS/2 port...
Which means debugging driver issues can be a PAIN IN THE ASS when your OS is hardlocked at a high IRQ!
 
PS/2 uses interrupt communication whereas USB uses polling communication.

Some gaming enthusiasts SWEAR they get better response by using PS/2 over USB.

Its also the 2nd most prioritized IRQ in a PC.

  • IRQ 0 – system timer (cannot be changed)
  • IRQ 1 – keyboard controller (cannot be changed)
  • IRQ 2 – cascaded signals from IRQs 8–15 (any devices configured to use IRQ 2 will actually be using IRQ 9)
  • IRQ 3 – serial port controller for serial port 2 (shared with serial port 4, if present)
  • IRQ 4 – serial port controller for serial port 1 (shared with serial port 3, if present)
  • IRQ 5 – parallel port 2 and 3 or sound card
  • IRQ 6 – floppy disk controller
  • IRQ 7 – parallel port 1. It is used for printers or for any parallel port if a printer is not present. It can also be potentially be shared with a secondary sound card with careful management of the port.
 
Oh the days of the old style PS/2 mechanical mouse with the ball, one hair and its all over the place.
 
Formula.350 said:
I was actually going to make this same point... except, when I looked at my MSI X370 Titanium, I was unable to locate a COM header... heh So I think even those are now probably included only sparingly, and in my mind I'd figure it'd be lower cost motherboards where the buyer is a person looking for an inexpensive system that is still capable of handling some legacy tasks.

Then again, there's always USB-Serial connectors (which I don't know how "reliable" they are these days, I know early on they were flaky).
There's also these, too...
View attachment 75576

But, I suspect most Super I/O chips on motherboards have native Serial support, and is probably the decision of the motherboard maker on whether or not to include a header.
Click to expand...

Serial is still often used to configure routers and managed switches

As for PS/2

latest?cb=20121119154813.jpg
 
I still use a PS/2 keyboard...motherboard manufacturers need to stop getting rid of features people still use...same with eliminating 5.25" drive bays
 
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