DL = physical drive where boot sector is located no output - track 0, sector 1 is loaded into address 0:7C00 and control is transferred there - not a preferred method for rebooting by applications. A better method is to set the word at location 40:72 to 1234h and jump to location FFFF:0 in ROM - memory is not cleared when rebooted through this interrupt - see WARM BOOT