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

Keith Thompson <[email protected]> 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
This public discussion message is non-binding and may contain errors
All trademarks and other things belong to their owners, if any.

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Jakob Bohm <[email protected]> writes:

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

Keith Thompson <[email protected]> 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 .

Indeed, at a pitch of 10, an 80 character line left 1/4"
margins on an US standard 8.5" wide sheet of paper.

The margin bell usually rang at 72 characters.

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On 01.04.2025 05:46, Jakob Bohm wrote:

[...]

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. [...]

Yes. Just as an addition; my typewriter has a ruler ranging from
column 0, 10, 20, to 80 - where the numbers were indicating the
left and the right bounds of the characters; i.e., 1st character
was between 0 and 1 - thus 80 columns total. As you say that was
also the standard width of the paper we use here (DIN A4, 21 cm).
The typewriter was used with configured soft bounds to not start
at column 0 on the left side but to keep some indent space and
also on the right side. Moreover the ruler continued a few (four)
characters before the column 0 mark and also after column 80; it
was possible to "unlock" that space on demand to exceed the soft
limit, or also the hard limit in case non-standard paper of larger
width would have to be used.

But it's noteworthy to mention that there were also typewriters
with wider carriages existing; I saw one in a tyres manufacturing
company. But these types were obviously rarer. I don't know whether
it's been used to type on A3 or on landscape A4 or on other paper.

Janis

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On 01.04.2025 15:52, Scott Lurndal wrote:

Jakob Bohm <[email protected]> writes:

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 .

Indeed, at a pitch of 10, an 80 character line left 1/4"
margins on an US standard 8.5" wide sheet of paper.

The margin bell usually rang at 72 characters.

By "usually" do you mean it was fixed but depending on the specific
machine? Or that the machine was typically configured by the typist
to rang with the 72th column?

The typewriter I have (just a common machine) had these soft bounds
you could set for the first and the last text column. The bell was
triggered *depending* on the right bound set; it rang with the 7th
character before the right bound reached, so that was when typing
the 73th character column only if you set the bound to 80 columns.
Typically you had not set the right bound to 80 columns because you
wanted some blank space (similar to the indent on the left side),
so the bell (with typical settings) rang before column 72.

Janis

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Janis Papanagnou <[email protected]> writes:

On 01.04.2025 15:52, Scott Lurndal wrote:

Jakob Bohm <[email protected]> writes:

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 .

Indeed, at a pitch of 10, an 80 character line left 1/4"
margins on an US standard 8.5" wide sheet of paper.

The margin bell usually rang at 72 characters.

By "usually" do you mean it was fixed but depending on the specific
machine? Or that the machine was typically configured by the typist
to rang with the 72th column?

Last time I used a typewriter was 1975; IIRC, the margins were
selectable on some models; I've a newsman's portable in storage somewhere.

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