Modify the BIOS startup item graphic tutorial

Now we can say that the floppy drive is no longer used, so when we need to enter the DOS interface, we need to run some software programs running under DOS, only through the CD with boot function Implement this functionality that was originally implemented by a floppy disk. Therefore, we need to modify the system default startup items, set the CD-ROM drive as the system's first boot device, so that we can ensure that the system is read first after the system is started. Now we can say that the floppy drive is no longer used, so when we need to enter the DOS interface, When you need to run some software programs that run under DOS, you can only implement this function that was originally implemented by a floppy disk through a CD with boot function. Therefore, we need to modify the default startup item of the system, and set the CD-ROM drive as the first boot device of the system, so as to ensure that the CD-ROM in the CD-ROM drive is read first after the system is booted, and the CD-ROM with boot function is booted into the DOS or boot interface.