In MM Digest 001231, Douglas Henderson speaks of chad and Robbie
adds that the term may have originated in the paper music roll
industry.  I am not sure where the term originated, but at one time
I worked with mechanical Teletype machines.  The data could be sent
by feeding a pre-punched paper tape through the tape reader on the
machine.

I recall that there were two types of tape used, "chad" tape and
"chadless" tape.  One had cleanly punched holes and on the other the
hole was cut on three sides and the bit of paper from the hole was
still attached and hanging from the fourth side.  So, "chad" is
certainly not a recently coined word.

Howard Wyman