I figured out the problem.  Ruby tr doesn't handle octal numbers like
perl does.  Not sure if it's just not implemented or maybe there is a
correct way to do it I'm not sure of.  In any case instead of trying
to use tr to map the octal numbers I just made an array of decimal
numbers for the even bit map and then made this function.  Works fine.


def setEvenParity(str)
  new = []
  str.each_byte {|b| new << @even_parity[b]}
  new.pack("C*")
end