[thakoppno]

One theory I saw argued the punch card size was the reason for 80x24. But why were punch cards that size? They were designed off of the cards used for the census. Why were the census cards that size? Because they were modeled after the dollar bill size.

I do love thought experiments like this but do believe they’re insatiably unresolvable.

[staplung]

And the reason they were modeled after the dollar bill size is because there were already many types of systems for storing and organizing them. That came in handy for the census.

The old BBC Connections series has a segment with James Burke using the old census tabulators.

https://www.youtube.com/watch?v=z6yL0_sDnX0&t=2640s

[ronsor]

In the end, all reasons resolve to either "it's what we had at the time" or "someone thought it looked good."

[rzzzt]

"Everybody just liked it that way and it costs too much to change it now": https://www.exocomics.com/743/

[theamk]

Not always, for example original CD disks had capacity of 74 minutes to accommodate Beethoven's Ninth Symphony.

[rasz]

That one also turned out a myth :) CD size was determined by Cassette tape dimensions (diagonal, human can still hold one in one hand) and that combined with conservative pits/lands/track pitch choice drove the play time.

thus CD runtime was derived from something "what we had at the time".

[antiterra]

The story as told may be inaccurate but it wasn’t simply ‘what we had at the time’ either.

The 74 minute length resulted from Sony rejecting the Philips 60 minute 11.5cm diameter “Pinkeltje” disc size in favor of a 12cm diameter.

It’s quite possible that Sony’s Norio Ohga simply argued that the 9th symphony or various operas fitting would be enough of an advantage for the slight size increase without meaningfully decreasing portability.

[rzzzt]

Meanwhile the LP crowd was flipping sides like it was Ultima VIII (slight exaggeration). Why would it be critical for a new format to do away with multi-disc releases if the customer base has already grown accustomed to them?

[rbanffy]

Because it was annoying to flip the disk in the middle of the thing.

[theamk]

You got any source for this?

The symphony story might be a legend, but it's pretty well known that the original design was somewhere in 10-11cm range, but this was eventually increased to 12 cm.

The "diagonal cassette size" seems extremely far-fetched - first, who cares about this? If you are worried about boxes, shelves etc.. you want horizontal size, which 10 cm. And you are worried about holding in hand, 12cm is not very convenient for the smaller hands, a smaller size would be better.

[rbanffy]

When respectfully handling them out of the box, I always stuck my index finger in the central hole and the thumb on the border. I have large hands but I rarely held them by the borders.

[tracker1]

If anything, I'd have guessed that the size of an 8-track in a car stereo was probably a larger influence on potential form factors for CD audio. Since car stereos were at least somewhat normalized in the early 80's. Not speaking to an adapter, just in terms of what would "fit" in a typical stereo hole in a car.

That said, I doubt that's the reality either... it's probably a number of factors. I am slightly surprised that a USB based read-only media format standard for players hasn't materialized, though it seems that online/rental models are what the industry really wants.

[rasz]

Source is Dr. Kees A. Schouhamer Immink. Philips’ principal engineer in the joint efforts of Sony and Philips to develop the Compact Disc (CD) https://www.turing-machines.com/pdf/cdstory.htm:

>The disk diameter is a very basic parameter, because it relates to playing time. All parameters then have to be traded off to optimise playing time and reliability. The decision was made by the top brass of Philips. 'Compact Cassette was a great success', they said, 'we don't think CD should be much larger'.

>As it was, we made CD 0.5 cm larger yielding 12 cm. (There were all sorts of stories about it having something to do with the length of Beethoven's 9th Symphony and so on, but you should not believe them.)

> The 8-14 bit channel code was agreed and all the specifications between them led to a playing time of 75 minutes.

[rbanffy]

> But why were punch cards that size?

Something related to the width of a two-horse Roman carriage… Not sure ;-)