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There is an apparent failure of the keyboard

Explanation: The keyboard appears to be bad. You are getting errors at boot time saying that the keyboard is not attached or has failed, or you are unable to get any characters to register on the computer.

Diagnosis: This is almost always a configuration or connection problem. It's extremely rare for a keyboard to fail outright; they're just too simple of a device to have a lot of failures. A common problem is having the keyboard not inserted fully into the connector on the motherboard.

Note: Remember to turn off the PC when switching keyboards. You won't likely damage anything by switching them with the power on, but the PC might not respond correctly.

Recommendation:

• Make sure you do not try boot the PC with a key pressed down on the keyboard. This will often cause the keyboard to register an error when the PC is started up.
• Keyboards for the original PC/XT used different electrical signaling than the keyboards used by all AT and later PCs. Most keyboards (except for extremely old ones) have a switch on the bottom to select between XT and AT mode. Make sure that the switch is set correctly (normally to AT for all 286, 386 etc. PCs) or the keyboard will not work.
• The simplest thing to try if you suspect a bad keyboard of course is to switch the keyboard with another one and see if the second one works. If it does, then swap back the first one. If the first one now works, it was inserted incorrectly before and should now be OK. If it still doesn't, it is bad and should be repaired or replaced.
• Make sure that the keyboard is inserted fully and completely into its socket on the motherboard. You may have to rotate the connector to make sure it lines up properly with the socket, and you may have to wiggle it and apply some pressure to get it entirely into the socket.

Warning: Some keyboards can be difficult to insert into some keyboard sockets, because of variation in the shape of the connector or the size of the pins. Do not try to force the keyboard into the socket. The socket is usually mounted directly onto the motherboard at a right angle and with little support. If you push too hard you may break the connector, which will ruin the motherboard.

• If you are attempting to run the PC without a keyboard (which is done sometimes for network servers or in other applications) make sure that you disable the BIOS setting that causes the PC to halt on a keyboard error.
• Make sure the keyboard cable is not being pulled, stretched or crimped, and that the point where it attaches to the keyboard is not loose.
• If your PC has an integral PS/2-style mouse port and a mini-keyboard port, these connectors are the same physical size and shape. Make sure that you don't mix up the keyboard and mouse ports or neither will work properly. Note that I have seen these two ports mislabeled on the back of the system case before!
• If you replace the keyboard with another, or if the original keyboard is tested on another PC and it works there, this implicates either the keyboard controller chip or the motherboard itself. Troubleshoot the keyboard controller here or the motherboard here.

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