It is quite astonishing. In EWD 139 – written in the first half of the 1960s – Dijkstra argues why their to-be build Dutch computer the EL (Electologica) X8 should no longer be equipped with a punch card reader. Looking back, for at least for twenty more years after this article (IBM) computers were still being equipped with punch card readers.
Photograph copyright Mr. J.A. Th. M. van Berckel.
Not only is Dijkstra very clear with his arguments, but he is so much opposed to the punch card that finds that having to write them down he finds, very Dijkstra-ish, a test of his decency. His arguments are the following.
The punch card technology has become obsolete. It is simply not needed anymore, there is paper tape now (this is the time before terminals and time-sharing).
The way you must use punch cards, the “style”, leads to local solutions for reliability (parity checks) instead of structural redundancy solutions over the entire document.
The limitation of 80 characters leads to technical “ad hoc” conventions and constraints, and limits the ability to improve the readability of programs.
Finally, Dijkstra argues that a single card does not have information value. You need the whole stack, on the right order. Which makes punch cards very impractical to use.
Dijkstra concludes the article that is so much a Dijkstra paragraph, that I can not leave it out.
“Hier wil ik het bij laten. Als mensen mij komen vertellen, dat zij met recht van ponskaarten gebruik gemaakt hebben, dan verandert die mededeling minder aan mijn opinie over ponskaarten, dan over de man.Ik concludeer dan, dat deze man voldoende inventief of ordelijk geweest is om van een in wezen ongezond middel gezond gebruik te maken. Als pleidooi voor het medium – ik kan niet anders – is zo’n mededeling zonder enig effect.”
In my imperfect english:
“I will leave it with that. If people come tell me that they have rightfully used punch cards, than that statement changes less in my opinion about punch cards, than about the man. I conclude then, that the man has been sufficiently inventive or orderly to use an essentially unhealthy tool in a healthy manner. As a appeal for the medium – I can not do other – such a statement is without any effect.”
