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 DISCUSSION OF PARITY

 Parity is a system that helps to detect errors in transmitted
 data.  Three "flavors" are possible; even, odd, and none.  Even
 and odd parity require that data be represented by 7 data bits.
 "No parity" can be used with 7 or 8 data bits, although it is
 almost universally used with 8 data bits.

 For even parity, the number of 1s in the binary seven-bit
 representation of a character is counted.  If the answer is
 odd, a 1 is transmited as the eighth bit; if the answer is even,
 a 0 is transmitted as the eighth bit.  Either way, the total number
 of 1s transmitted in eight bits is even.

 For example, the 8 bit ASCII code for "C" is 01000011.  Dropping the
 first zero leaves 1000011.  There are three ones in this, so we replace
 the deleted zero with one, and transmit 11000011 for "C".  If the other
 end is also set for even parity, it will read this as "C". If the other
 end is an IBM PC and is set for no parity, it will read this as "|".

 Odd parity would be the same, except "C" would be transmitted as 01000011.

 In general, if you are setting up a connection and don't know what
 kind of parity to use, use none.  If about half the characters transmitted
 to you appear as garbage, switch to even parity (and seven data bits).