 Bradley, as the chief engineer of the IBM PC project and developer of the machine's ROM-BIOS, had originally used
, but found it was too easy to bump the left side of the keyboard and reboot the computer accidentally.According to his own account, Mel Hallerman, who was the chief programmer of the project, therefore suggested switching the key combination to as a safety measure, a combination impossible to press with just one hand on the original IBM PC keyboard.The feature was originally conceived only as a development feature for internal use and not intended to be used by end users, as it triggered the reboot without warning or further confirmation—it was meant to be used by people writing programs or documentation so that they could reboot their computers without powering them down.