I would like to buy a keyboard USB to PS/2 adapter. However on many websites I see Mouse USB to PS/2 listed separately than Keyboard USB to PS/2 adapters/ I wonder if they are internally identical or if they are different (i.e they map some USB pins to some different PS/2 pins)
1 Answer
They are very different.
A USB to PS/2 converter is not a straight-forward wiring pin-out adapter between the 2 different connectors.
The converter contains a small chip that talks PS/2 (either the keyboard or the mouse version) to 1 connector and that acts as a USB device (which involves being able to correctly respond to various USB commands) to the other connector. This USB device must (among other things) identify itself to the computer as either a "USB HID mouse" of a "USB HID keyboard" as appropriate.
There are converters that have 2 PS/2 connectors so you can connect both a mouse and a keyboard to 1 USB port. Internally such converters identify themselves to the computer as USB device with 2 sub-devices (the USB standard allows for this).
Allegedly there also exist "smart" converters that can work with either a mouse or a keyboard and will auto-detect what is attached. I have never seen one myself so I can't tell you how well that works.
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