Re: 80 char lines and holerith cards [Was:Which code style do you prefer the most?]

On 2025-03-21 10:41, Tim Rentsch wrote:

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
 

IBM developed 80-column cards, with the same overall size, in
the late 1920s.  Apparently 80 just happened to be the number
of rectangular holes that could reasonably be accommodated
[...]

 We don't know that.  The same size might have accommodated 85
columns, but was revised down to 80 for other reasons.  Or the
same size might have accommodated only 77 columns, but it was
discovered that 80 columns could work if a different card
material was used.  The form factor was one constraint, but
not the only constraint, and not the only consideration.
 

Source: <https://en.wikipedia.org/wiki/Punched_card>
>
I'll just note that the fact that 80 is an arbitrary number,
based on technologies we no longer use, [...]

 The choice of using 80 columns was constrained by what technology
was available at the time, but it's wrong to describe the value
as arbitrary.  We know that a choice was made between a much
lower number (between 40 and 50 IIRC) and the higher number 80.
That decision already means the value used was not arbitrary.
Also we don't know what other factors might have gone into the
decision;  it's possible that IBM settled on 80 only after
considering what line lengths needed to be supported.  We don't
know what would have happened if, for example, it had been
discovered that using rectangular holes would allow up to only
60 columns, perhaps encouraging the introduction of newer
equipment.  We also don't know if someone had looked at how
many characters were needed in typical printed material, and
pushed the rectangular hole technology only as far as was needed
to support that.  It seems reasonable to expect that IBM would
have considered such issues, even in the 1920s, and not just
ignore them.
 

Another likely inspiration at the time would be the number of
characters per line on ordinary office paper of the period using ordinary typewriters of the period .  Record keeping clerks would be experienced in fitting tables of data in that limit, and some machines would need to output the contents of cards as text on regular sheets
of paper suitable for existing archival storage places, such as the
binders used for collating official/business correspondence .  At the
time, punched cards were a temporary storage medium for data processing,
sometimes used as an input medium, but rarely as the output format.
Data older than use of typewriters would be hand written on the same or
similar paper sizes, loose sheet or in already bound ledgers .  Some
organizations had kept records in those formats for 1000+ years already.
I also believe the format was a few decades older than 1920, which
would still fit the theory .
   Enjoy
   Jakob
--
Jakob Bohm, MSc.Eng., I speak only for myself, not my company
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