Interrupt 19h	Bootstrap Loader
(0:0064h)       Reads track 0, sector 1 into address 0000h:7C00h, then
                transfers control to that address. If no diskette drive
                available, transfers to ROM-BASIC Int\18 or displays loader
                error message. Causes reboot of disk system if invoked while
                running. (no memory test performed).
note 1) This doesn't work on many machines, use
	MOV BX,1234	;No memory test
		-or-
	MOV BX,0	;Test memory
	MOV AX,0040
	MOV DS,AX
	MOV [0072],BX
	JMP FFFF:0000
     2) If location 0040:0072 does not contain the value 1234h, a memory test
        will be performed before reading the boot sector