Bootloader jumping to next boot device

Question

So far I've managed to write a simple bootloader using NASM which prints 'Hello world' and then hangs. This bootloader is 512K long and it's stored in a pendrive's MBR. The BIOS is configured to first boot the USB external device and then the hard drive with the corresponding operating system. Like I said before, the bootloader just hangs after printing 'Hello world' because of a never ending loop instruction (jmp $). So, I would like to know if it's possible to continue with the boot sequence (jumping to the next boot device) after the bootloader has finished it's execution. Is there a way to continue with the OS execution (from the HD) after printing 'Hello world' from the pendrive? Which instruction or interruption would accomplish this?

Thanks in advance.

Answer 1

Well, it's solved now. INT 0x19 will do the trick.

Answer 2

On BIOSes compliant with the BIOS Boot Specification INT 0x18 should try the next boot device.

INT 0x19 restarts the boot process, possibly a full reboot.