Objectives
 - Bitwise operators and how to use them


  1   bit
  0   bit
  1001 nibble (4 bits)
       Can be represented by 1 hex digit (0-F)
                      ... or 0 to 15  (== 0 to 2⁴-1)
  10011010 byte
       Can be represented by 2 hex digits (00-FF)
                      ... or 0 to 255 (== 0 to 2⁸-1)
                      ... or 1 ASCII character
                          (incl extended ASCII, ≥128)
In memory, everything is bytes.
In files,  everything is bytes.
There are no data types for bits or nibbles.