TRUE or FALSE.  A light is either ON or OFF. In your
       computer, a bit is represented by the voltage on a wire: it
       is either HIGH (near 5 volts) or LOW (near 0 volts). The
       high value we associate with the symbol '1'. The low value
       we associate with the symbol '0'. In order to represent
       members of larger collections of objects- letters of the
       alphabet, for example, or large numbers, binary digits must
       be grouped together.
           Four binary digits taken together can represent 16
       different objects. (Two to the 4th power.) Eight binary
       digits taken together form a unit called a 'BYTE' in
       computerese. A byte can stand for any one of two to the 8th
       power (or 256) different objects. Your computer deals in
       'BYTE' sized Information units. Data flows from one part of
       your machine to another along eight wires called the data
       bus- in bytes.
           In order to specify exactly what information Is being
       accessed at a given instant, your computer sends out an
       'ADDRESS'.  This address is a 16 bit binary quantity that
       flows along 16 wires called the address bus. Since there
       are 16 address lines, two to the 16th power, or 65536 unique
       addresses can be specified by your machine.
           Now, instead of using binary numbers directly like your
       computer does, it is customary to consider binary digits in
       groups of four. Each possible value of this group is denoted
       by a symbol: the numbers from 0 to 9 plus the letters A
       through F. These are called 'HEXADECIMAL' numbers.
       Accordingly, we have the following:

                     BINARY          HEXADECIMAL         DECIMAL

                      0000                  0                 0
                      0001                  1                 1
                      0010                  2                 2
                      0011                  3                 3
                      0100                  4                 4
                      0101                  5                 5
                      0110                  6                 6
                      0111                  7                 7
                      1000                  8                 8
                      1001                  9                 9
                      1010                  A                10
                      1011                  B                11
                      1100                  C                12
                      1101                  D                13
                      1110                  E                14
                      1111                  F                15
                     10000                 10                16


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