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All About Bits and Bytes

Data is made up of bits and bytes. A bit is the smallest piece of information that can be created or stored. A bit can either be a ?0? or a ?1? in value.

A byte is made up of 8 bits. The 8 bits in a byte are stored in various combinations (up to 256 possible) to represent different characters, symbols and program commands. For example, in a text document, each displayed character is represented by a byte. Non-printing characters that specify things such as formatting and graphics are all represented by a series of bytes.

A file is made up of hundreds or many thousands of bytes. Large image files may be millions of bytes. So for convenience, we introduce the scientific notation to represent larger numbers:

• Kilo     = thousand = 1,000

• Mega  = million = 1,000,000 or 1000 Kilo

• Giga   = billion = 1,000,000,000 or 1000 Mega

So,

• One Kilobyte (or KB) is 1,000 Bytes.

• One Megabyte (or MB) is 1,000,000 Bytes or 1,000 KB

• One Gigabyte (or GB) is 1,000,000,000 Bytes or 1,000 MB or 1,000,000 KB
  
  
  
  In comparison:

• Your PC random access memory (or RAM) may store from 64 MB to 512 MB or more.

• Your PC hard drive capacity may be 20 GB to 120 GB or more.

• A memory card used in a digital camera stores from 8 MB to 256 MB or more.

• A ?Zip? drive stores from 100 MB to 750 MB.

• A CD-ROM stores just over 700 MB.

• A DVD-R stores 4.7 GB.

• A floppy drive (A:) stores 1.44 MB. Not very much in comparison to other storage media!
  
  To put this in the context of file size:
   

• A typical word processing file may be anywhere from 20 KB to over 100KB in size.

• A digital image file from a digital camera may be 200 KB to 2 MB in size.
  
  And in the context of network or connection rates:
   

• A dial up modem operates at 56 Kbits per second, which is equal to 7 KBytes per second remember, there are 8 bits to a byte).

• A broadband modem (cable or DSL) operates at 128 Kbits to 2 Mbits per second; equal to from 16 KBytes/s to over 250 KBytes/s.