JSI Tip 5416. How can I pause the Windows boot process on a black screen?

While the boot loader is active, you can press the ESC key to pause the boot process on a black screen.

To resume the startup process, press any other key.

Why does the ESC key pause the startup process?

The boot loader checks to see if you press the F5 or F8 keysduring startup. These function keys have a 3 byte key code, where the first byte happens to be the same as the ESC key. When you press ESC while the boot loader is checking for an F5 or F8 key press, the key buffer only contains one byte and the boot loader waits for the next key to be pressed.