For several years, I worked a lot with punch cards. In those days, punch cards were totally innovative. They meant an end to those stupid strip cards and more flexibility. In punch cards, it was possible to insert some text of your own (which was absolutely impossible with the strip cards).
The punch card in this picture (which, by the way, is taken from wikipedia) contains 40 symbols. Our punch cards were more modern than that and contained 80 symbols (columns in our “sheets”, also known as programming forms which we filled in with pencil and were given back as a package of stamped punchcards. What a programming method!).
You had to mark column 72 if the program continued on the next card. The text fields from column 73 on were reserved for numbering. Column 71 was reserved for something special (it might have been a commentary symbol or something of the sort – I no longer remember). The first 70 columns were the “useful symbols”, dependent on the language, sometimes further structured.
Whenever you started a program, you were wise to number in steps of 100. That left enough space for adding extra cards. Incidentally, it was very important to do the numbering, because whenever such a pile of punch cards accidentally fell down, you were able to retrieve the program.
Compared with the new magnetic EDP media, where a simple magnetic field could destroy everything, many programmers found this a real advantage. My argument that punch cards might also fall into the water and then be damaged was never really taken seriously. It was not meant seriously (though some people believed it was).
Yes, and twitter permits 140 digits. I wonder where that originated. Or could it be a coincidence? I am sure some old IT rabbit decreed that the equivalent of two punch cards must be enough!
One SMS may have 160 digits. That is really a disappointment. I would have preferred 140!
But to be perfectly honest: as much as I enjoy blogging, the worlds of twitter and such still fascinate me. As one of my former teachers used to say: “Brevity is the Soul of Wit“.
RMD
(translated by EG)
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