First post, by cprieto

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This is maybe a super basic question but I thought this will work:

Old mobo only supports AT connectors for keyboard
I only had a USB keyboard
I have an AT to PS/2 converter
I have a PS/2 to USB converter


For my surprise it doesn't work... My simple question, why? I suppose it have to do something with the USB protocol and new keyboards but I will really love to know more about why. Can somebody guide me in my search for understanding this problem a little more? I will highly appreciate it!


Reply 1 of 5, by maxtherabbit

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The answer is the USB to PS/2 adapter. The input device has to be specifically designed to support both USB and PS/2 modes for this adapter to be of use. You can't just hook any USB keyboard up to it and expect it to work

Reply 3 of 5, by aha2940

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USB keyboards use a protocol to communicate over USB port. Some USB keyboards, also support PS/2 protocol (completely different from the one used for USB), which is used to communicate over PS/2 ports, when using the adapter. The adapter is completely passive, all it does is connect the PS/2 port wires to the correct ones on the USB keyboards's port, nothing more. When the keyboard supports both communication protocols, it will detect upon connection which one should use an go with that. Unfortunately, it's not really predictable if a random keyboard (applies to mice too) will support or not both protocols, however most new keyboards are USB-only. Your best bet would be getting a keyboard known to support both (oldie Microsoft keyboards come to mind, just like Logitech ones).