To do this (assuming you have a bootable DVD ROM - i.e. one with an operating system on it), you need to tell your PC's BIOS to look at he DVD drive during the boot sequence and make this the first drive to try and boot from.
To do this you need to get into the BIOS menue - you PC manual will tell you how to do this but you can also try pressing the one of the 'F2', 'F8', 'F9' or 'F12' keys while the PC is starting up (before windows loads), one of these should work! - and change the boot menue options.
DVD ROM, Hard drive and NIC
A CD ROM drive cannot read a DVD. So it is not possible to use a CD ROM as a DVD ROM. A DVD ROM drive can work with a CD though.
A CD-ROM drive is not needed to boot the computer. Just put the hard drive first in the boot order in the BIOS.
USB drive and DVD ROM
DVD is the same as DVD ROM, i think? either that or it means the drive you put the DVD/CD in. the drive is where you put the disks, (for all of you cave men). SO EITHER dvd MEANS DVD ROM or ROM is where you put the dvd
Both internal and external hard drives can be removed from a computer provided that the PC does not boot from any of them. In that case, the first boot device would have to be a removable drive like CD-ROM/DVD-ROM or floppy drive.
You cannot play a DVD in a CD-ROM drive, you need a DVD compatible drive in order to play a DVD.
No. A cd-rom drive cannot play DVD's. A DVD drive can play CDs and DVD's. A cd-rom drive isn't made for DVD's. It's made only for CD's, and it can't write any. It can only read.
To play DVD's
dvd
No, the Retina display model does not have a DVD-ROM drive. You can buy an external drive if need be.
Yes, it does.