shutdown pc, without os or third party power Management

HI I'M TRYING TO BUILD A STANDALONE COMPUTER SOFTWARE SSYTEM, NO THIRD PARRTY STUFF, OTHER THAN TO BUILD AN ASSEMBLY INTERPRETER. DOES ANYONE KNOW HOW TO SHUTDOWN THE PC WITHOUT USING AN OPERATING SYSTEM COMMAND, KERNEL COMMAND OR ACPI, OR SIMILAR. BIOS INTERRUPTS AS ACCEPTED. DOES THE COMPUTE AUTO-TYURN OFF WHEN THE BOOTLOADER COMPLETES, I'VE TRIED OS DEV, YET CA'T FIND ANYTHING SUSTANTIAL.