HP 2116 and its fotoreader

You may not have called it a fotoreader. You might not have known it at all, you never knew it. Today you may imagine it as the slim slot for SD cards.
   For the HP 2116 mini computer, and for many other computers and machines of at least a decade back in the sixties and seventies, the photoreader (with ph, or European style, with f) was the most important peripheral of all, before magnetic tape units or later (drums and) discs. Storage was not in magnetism but in holes (not quite like on a CD). Binary holes had a tradition, for example with train tickets … A punched hole in the carton invalidated them.
   A fotoreader did not scan pictures, as you might assume, it read digital data from punched tapes. These tapes were kept in small square white cardboard boxes, handy.
   If you had no fotoreader, you had to read software into a computer with the speed of ten characters a second with a Teletype, see http://blogabissl.blogspot.com/2017/10/listening-to-compter-bugs.html. The fotoreader read 300 to 500 cps, characters per second, depending on model, a speed increase of fifty times! We felt like driving 200 km/h on the Autobahn instedad of 40 km/h in town.

The HP 2748 optical paper tape reader (1969 to 1983) read 500 cps and was priced at $ 1500. Picture HP Museum
(The paper tape should have been threaded correctly around the black wheel at upper left.)

Many types of optical readers, especially from Facit, were popular, as paper tape was the principal storage “unit” for digital data, including programs.
   When I became one of the tree first “systems engineers” of HP in Europe back in 1969, I was first trained in Böblingen, Germany, and in Slough, England.
   The first thing to learn – even for software engineers – was adjusting the brightness of the lamp in the reader. Reading errors were a pest. If you didn’t get your tape read, you had to go back to the Teleype – and eat lunch while it rattled along reading your tape. Mechanical reading was a strain on the tapes too.

“European” 5-hole and “American” 8-hole paper tape for Telex and TWX machines, Wikipedia
The small holes were just for transport. You “scatched” data by punching out all holes.
If required you could make 5-hole tapes by punching row 3 from bottom all along and cutting or ripping off the small stripe. 

To fix a ripped tape Scotch tape was not very practical, as you had to repunch the holes. So we had onesided glued tapes with all holes punched to join two tapes. In practice you had to reproduce all the tape, a noisy and slow process. Many systems needed an extra tape punch – remember Teletypes did only 10 cps –, for output of data, perhaps for CNC machines or for your own computer system when compiling programs as intermediate or final program tapes.
   Typically computers were used both to run and to program programs. Try to program an App on (not just for) a smartphone today! My Psion organizer has a compiler built in, it’s autonomous, and I’ve made numerous little programs while idling in the sunshine at seaside.
   Paper tapes for frequent use were punched in Mylar. So they were strong and didn’t rip.
   Later fotoreaders got automatic brightness control.
   Originally, however, a screwdriver was the programmer’s best friend.

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