; boot1.asm   stand alone program for floppy boot sector
; Compiled using            nasm -f bin boot1.asm
; Written to floppy with    dd if=boot1 of=/dev/fd0
	
; Boot record is loaded at 0000:7C00,
        ORG     7C00h
		
; load message address into SI register:
        LEA     SI,[msg]
		
; screen function:
        MOV     AH,0Eh
		
print:  MOV     AL,[SI]         
        CMP     AL,0         
        JZ      done               ; zero byte at end of string
        INT     10h                ; write character to screen.    
        INC     SI         
        JMP     print

; wait for 'any key':
done:   MOV     AH,0       
        INT     16h                ; waits for key press
                                   ; AL is ASCII code or zero
                                   ; AH is keyboard code

; store magic value at 0040h:0072h to reboot:
;		0000h - cold boot.
;		1234h - warm boot.
        MOV     AX,0040h
        MOV     DS,AX
        MOV     word[0072h],0000h  ; cold boot.
        JMP     0FFFFh:0000h       ; reboot!

msg     DB      'Welcome, I have control of the computer.',13,10
        DB      'Press any key to reboot.',13,10
        DB      '(after removing the floppy)',13,10,0
; end boot1