I have an old laptop with a PS2 port and it has a mouse symbol on it. Does this mean I can only plug a mouse into this port and will a keyboard work?
As an experiment, I dug up an old desktop with PS/2 connectors, connected the keyboard and mouse backwards, the keyboard did not light up or work while in the BIOS, Windows loaded and the mouse or keyboard did not work, the Windows hardware wizard said it installed a new device and to reboot.
I rebooted, but still they did not work, so I hot unplugged the devices and connected them to the proper ports, the mouse still did not work but the keyboard came to life. Both worked after another reboot.
So no, they will not work when connected to the wrong PS/2 ports on a desktop computer.
Next, I connected a keyboard to the PS/2 mouse port on my old Dell Latitude D600 notebook, booted Windows XP, the keyboard does not work or light up any lights, and the hardware wizard did not show up.
It's a bust. No, it will not work.
...end of smoke test...
According to Wikipedia probably not:
The pinouts of the connectors are the same, but most computers will not recognize devices connected to the wrong port.
Like the man said, "It really depends on the laptop." Some laptops had just one PS2 port and you could plug either a mouse or a keyboard into it and they both worked, just not at the same time, of course. So the answer to that was if you wanted an external keyboard, plug it into the PS2 port and use the USB port for the mouse. Or use the onboard mouse pad. You could also do the same if you wanted an external PS2 mouse. Then you needed to plug a keyboard into the USB port if you wanted an external keyboard as well. By the way, it's never a good idea to change a PS2 port's device when the computer is on. You're taking a very unnecessary risk of damaging your computer.