Q68805

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page	Q68805: How to Reboot Your Machine Within a MASM 5.10 Application	/pubs/pc/reference/microsoft/kb/Q68805/

Q68805: How to Reboot Your Machine Within a MASM 5.10 Application

Article: Q68805
Version(s): 5.10
Operating System: MS-DOS
Flags: ENDUSER | S_QUICKASM
Last Modified: 6-FEB-1991

You can perform a complete reboot (cold boot) on an 8086-based machine
by jumping to the address F000:FFF0. This action also reboots many
80286 and 80386 machines. The address contains a jump instruction that
leads to the machine's initialization code. For this method to
succeed, your machine must be in real-mode operation.

To prevent a memory check on IBM and many compatibles (warm boot), you
should store the value 0 x 1234 in the memory location at 0040:0072.
On 100-percent IBM BIOS compatible machines, an alternative method
is to call int 19h instead of jumping to the address mentioned
above.

Code Example
------------

    .MODEL SMALL
    .CODE

Start:
    mov ax, @data                 ; Load ds with data segment
    mov ds, ax

    mov ax, 40h                   ; These three lines cause a memory
    mov es, ax                    ; test NOT to be performed. To
    mov WORD PTR es:[72h], 1234h  ; do a memory test, remove them.

    jmp DWORD PTR b_vec           ; Jump to the reboot address

    .DATA
b_vec   DW 0FFF0h                 ; Offset of reboot vector
        DW 0F000h                 ; Segment of reboot vector
    .STACK
    END Start