Douglas G. Wilson
douglas at NB.NET
Sun Jan 14 02:27:50 UTC 2001
> The earliest attestation thus far for "chad" is 1947 (from the
>files of Merriam-Webster). Here now is one from a few years earlier:
>_American Telegraphy After 100 Years_, by F. E. d'Humy,
>Vice-President and Chief Engineer, and P.J. Howe, Assistant Chief
>Engineer in Charge of Engineering Economics, The Western Union
>Telegraph Company. Published in Supplement to the "Transactions of
>the A.I.E.E.," volume 63, 1944, pages 1014-1032. Later reprinted
>separately. --(A.I.E.E. = American Institute of Electrical Engineers).
> The copy I obtained is the reprinted one. Page 16, col. 3 says:
> 'One of the equipment differences between the Western Union
>and Postal Telegraph switching systems is that the printer-perforator
>used in the latter is essentially a "typing reperforator," which uses
>a narrow tape and prints the characters right over the code
>perforations. In order to obtain readability,the holes in the tape
>are punched only part way,eliminating the "chad" and thus providing a
>complete surface to receive printing, although still leaving the
>holes free for entrance of the transmitter pins.'
Good show! I reviewed that volume of AIEE Trans. today, and it's about the
same in the original journal form. Note that there's no explanation of the
meaning of "chad", suggesting that the term was already familiar in the
industry at the time -- but there are quotation marks! There seem to be no
useful references. Similar material was published in 1943 (IIRC) but it
didn't include that part.
The technology was remarkably stable way back. Paper tape (Wheatstone tape
[with chads!]) was virtually unchanged from ca. 1860 to the late 1920's,
apparently, and the subsequent tapes weren't all that different.
>... which headed me in the right direction of radiotelegraphy.
But it doesn't need to be "radio-": wired telegraphy used the same sort of
tape. The subject indices in AIEE Trans. and elsewhere tend to list this
sort of thing under "telegraph", "telegraphy", "telegraph equipment",
"teletype" (back to about 1930), etc. If anyone has some other good terms
to look for in the indices, please let me know.
-- Doug Wilson
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