Video memory enhances the ability to view text, photographs, illustrations or even movies. Video memory and processing capabilities may be upgraded by adding new Video Processing boards to a computer's internal expansion slot. Some computers include video boards that allow you to connect a VCR, TV or Camcorder to input and output video images. If we considered RAM your working space on a desk, then the desk drawers would be the hard drive, where you store programs and data files. Hard disk space is measured in bytes like RAM, but the hard drive has a much larger storage capacity.
Many desktop computers come with a CD-ROM drive, used to run programs and software.
A CD is a Compact Disc and stores about 650MB of memory per disc. Some CD you can only record on once, and others may be reused, erased and recorded over numerous times. However, unlike a cassette or other magnetic storage devices, CD quality is digital, therefore leaving no room for distortion. A DVD is a Digital Versatile Disc and stores about 4.7GB to 17GB of memory per disc. Most DVD drives can also read CDs.