Keyboards not registering keypresses at bootup

When Macs boot up, users have the option to provide key sequences for various boot options: reset PRAM, select boot volume, single-user mode, etc. However, some users may experience problems were

wbetters:

"I cannot use any keyboard commands while booting with my iMac. I thought I was going nuts so I tried it on my MACBOOK and they all work fine. It won't let me use C, T, option, command S, command V, nothing."

Users can check whether or not boot parameters are properly working, by modifying the NVRAM entries in the terminal. To do this, open the terminal and enter the following:

• sudo nvram boot-args="-v"

This will boot the computer in "verbose" mode. Other options include supplying "-s" for single-user mode. If the computer boots as expected, users can then reverse this by entering the following command to clear the boot arguments:

• sudo nvram boot-args=""

Depending on the computer's configuration, there may be two known reasons why keyboard inputs may not be registering at boot.

Firmware password set When firmware passwords are set on the computer, most boot arguments cannot be passed to the computer. The only option is to hold the options key to select the boot device, but even this will first prompt for the user's firmware password. If this password is set, users will first have to unset it before they can provide boot arguments. While certain hardware changes can reset the password, the recommended method for doing this is to boot off the Leopard DVD (using the "Startup Disk" system preferences or the "options" key at boot) and then use the "Firmware Password" option in the "Utilities" menu of the OS X installer.

Aluminum keyboards There is a known problem with the new Aluminum keyboards where some mac models may not recognize them until the system has loaded. It is recommended that all Aluminum keyboard users with input problems be sure to apply the keyboard firmware update that was released last April.

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