Silly question perhaps … I'm told that PS2 technology dates back to the early 1990's or thereabouts. By and large, motherboard manufacturers still support PS2 technology/ports instead of providing an additional couple of USB ports for keyboard and mouse. Is there any distinct advantage that a PS2 port has over a serial/USB port?
Not that I have anything against manufacturers continuing to support PS2 (+: My Logitech First mouse dates back nearly a decade and has seen 3 computers already
Best Answer
Yes! Some operating systems just won't work with USB keyboards or mice. Furthermore some operating systems may not have right USB drivers available during installation which could cause problems with OS installation. Sure, such problems are rare now (but could resurface due to USB 3), but for device manufacturers it pays to have compatibility with older standards.
Now on the hardware side the benefits of PS/2 are clear. The required drivers are much simpler to work with and can be loaded at much earlier stage than USB drivers so PS/2 can be helpful when restoring damaged operating systems which "hang" during certain part of boot process. Another point is that PS/2 KVM switches are easier to design and cheaper to manufacture. Finally the main point is that PS/2 connector itself is relatively small, not very difficult to use and it is sufficient for keyboard and mouse use. As far as response times are concerned, this answer claims that PS/2 actually has an advantage over USB devices.
Another "benefit" for PS/2 is that it is deeply entrenched, old and proven standard and therefore has support of manufacturer "inertia". As we can see when analyzing computer history, it took some time for USB to replace existing serial and parallel ports as well as certain proprietary connectors even in situations where it had significant speed and usability advantage. In current situation from what I can see, USB doesn't have that many advantages when used to connect mice and keyboards to desktop computers where the only major disadvantages of PS/2 are that the connector isn't as easy to plug in as USB and official hot-plugging support which has been mostly back-ported into current systems which use PS/2.