Make USB pen drive as a bootable device

If you can not boot from DVD / CD-ROM drive, but you can not boot using a USB device, like USB pen drive, the following alternative boot method is available:
To boot using a USB pen drive, use the dd command to copy diskboot.img image / images / directory of the DVD or CD-ROM-enabled. For example:
dd if = diskboot.img of = / dev / sda
Your BIOS-enabled must support booting from USB device for this boot method to work.