[GreenKeys] STUNTRONIC Parity Detector

[Jim Haynes]

I know some of the history behind this.  Working on Dataspeed Type 2 about
1963 we realized it would be trivially easy to add a parity check to the
transmitted data, since the bits of a character were being shifted through
a register and we would only need to add a flipflop that would change
state on each mark bit.  So we hacked up the system in the lab to add
this feature.  We started out calling it "error detection" and soon 
learned that would not fly because (1) the System did not want the 
customers to imagine that errors were possible, and (2) it only detected
some of the possible errors, and (3) how would it be used operationally?

If there was a transmission going on with operators watching then they
could interrupt it and start over.  But if the transmitter was unattended
and being called up at night what should be done?  Denounce the whole
transmission and repeat it the next day?  Or accept it and try to make
the best of it?

Eventually the name problem was solved by calling it "vertical parity
check" which is exactly what it was.  But I don't know if the feature
was ever offered in the production equipment.