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Summary
• Computers function based on the binary system, where on is represented
by a one (1) and Off is represented by a zero (0).
• A Bit is the smallest memory unit. Bit stands for binary digit.
• Eight bits make one Byte. A byte equals one character (letter, number, or

symbol).
• 1,024 bytes make one Kilobyte (K or KB) which is equivalent to a one-
page, double-spaced letter.
• 1,048,576 bytes make one Megabyte (M or MB) which is equivalent to a
novel.
• 1,073,741,824 bytes make one Gigabyte (G or GB) which is equivalent to
an encyclopedia set.

• 1,099, 511,627,776 bytes make one Terabyte (T or TB) which is equivalent
to a small bookstore.
• RAM: Stands for Random Access Memory. This is computer’s main
memory, which is used to process information. You can read from and
write to RAM. RAM is volatile, and any data disappears when you shut off
computer.

• ROM: Stands for Read Only Memory. This is the computer’s low-level
memory, which is used to perform its most basic functions. You can read
from, but not write to ROM.
• CD-ROM: Stands for Compact Disc-Read Only Memory. A CD-ROM
drive lets you instal programs, run CD-ROM based programs, and play
audio CDs. A CD-ROM holds about 650MB of information.
• CD-R: Stands for Compact Disc-Recordable. Lets you permanently write

or burn information.
• CD-RW: Stands for Compact Disc-ReWritable. Can be written to and
modified many times.
• DVD Drive
• DVD: Stands for Digital Versatile Disc. A DVD disc looks like a CD-

ROM, but can store much more information.
• Recordable and ReWritable DVDs: There are several competing, non-
compatible formats out there, including DVD-R /DVD-RW and DVD+R/
DVD+RW.
• Floppy disks are slow and can only store 1.44MB. They are all but