Although punchcards have been around since the early 1800's when they were used by a French silk weaver called Joseph-Marie Jacquard ( Jacquard invented a way of automatically controlling the warp and weft threads on a silk loom by recording patterns of holes in a string of cards), they were first read electronically in 1881 by Herman Hollerith for the US ( that would be United States, not University of Stellenbosch ! ) census bureau. The method of reading the cards remained virtually unchanged until they became obsolete in the 1970's. Cards would pass through a reader, moving between brass rods. Where holes were punched, the rods could touch and current could flow.
Here are the two standard types of punched cards used in first, second and
third generation computers. One of the primary problems of punchcards was that
read and write operations were carried out by separate machines. The data encoded
on the card was also printed on the card to facilitate organisation. Of course
it is hard to make little holes in paper without making lots of little bits
of paper and this debris of the card punch machine was commonly referred to
as chad. There Some claim that the word derives from the Chadless keypunch (named
for its inventor), which cut little u-shaped tabs in the card to make a hole
when the tab folded back, rather than punching out a circle/rectangle; it was
clear that if the Chadless keypunch didn't make them, then the stuff that other
keypunches made had to be `chad'. There is a legend that the word was originally
acronymic, standing for "Card Hole Aggregate Debris", but this acronym was probably
created long after the name came into being.
Paper tape was initially used in telecommunications (telex), and in the printing industry as the input medium for hot-metal typesetting machines. Today it is still in use for numerical control of milling and drilling machines From the early days of computing untill wel into the 70's, paper tape was commonly used in the computer industry as a cheap and reliable means of data storage. For heavy duty applications, paper was often replaced by synthetic materials like mylar. In computer applications, tapes were usually 1 inch wide with 8 information hole positions and one sprocket feed hole in each row. One meter of 8-channel tape can contain about 400 bytes of data. Paper tape punches with operating speeds from 10 - 300 rows per second have been built. Tape readers worked either mechanically (with pins as described above) or electro-optically. Using the latter technique, very expensive readers could handle up to 2000 [3] rows per second while being able to stop on one row. For such fast readers, special equipment (servo-controlled reels) was needed for feeding the tape to and from the reader. A simple solution used with medium-speed readers (300 rows/s) was to use fan-fold tape, which re-folds automatically as it is caught , in an appropriately dimensioned receptacle upon leaving the reader. Special equipment existed for comparing tapes: for critical applications, data entry was often done by two typists at the same time. typing errors could be detected by comparing the resulting tapes. Paper tapes could be corrected, edited or repaired easily by manually adding missing holes, or by cut-and-paste operations, using some very simple mechanical tools.