Simon could boot into DOS and try all the keys on the board
The Windows XP boot process is made up of several sections, represented by several different screens. During one of the screens, when the screen background is black, you can press the ESC key, and the boot process will pause until you press another key. During this screen, the system is waiting to see if you press F5 or F8 to choose other boot options, so pressing ESC causes it to wait indefinitely.