IBM, sonic delay lines, and the history of the 80×24 display
righto.com39 points by rbanffy 5 hours ago
39 points by rbanffy 5 hours ago
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.
In the end, all reasons resolve to either "it's what we had at the time" or "someone thought it looked good."
From a linked article on shift registers:
> To avoid these astronomical prices, some computers used the cheaper alternative of shift register memory.
Might be a direction for 2026 too?
Tangentially related: is there a history covering IBM's development of microcomputers? It is clear that the traditional story of the development of the IBM PC leaves out many important details. There the 5100/5110/5120, which goes back to the mid-1970's and reflects the stereotype of IBM. There is also the System/23 DataMaster, where the hardware seems to be the basis of the IBM PC. This seems to go against the traditional story that the IBM PC was some sort of renegade project. (If anything, they appear to be companion projects. The main difference being the DataMaster's focus upon IBM firmware/software.)
Man. I love the design of old terminals, computers, and such.
I am, also, extremely glad that these form factors were abandoned. Having an old terminal, it is possibly the least ergonomic machine I have ever used.
Deeply fascinated by these historical threads. It is precisely the various design choices made throughout history that have shaped the computer systems we use today.
No idea if this was a factor, but 80x25 on the IBM PC allows for showing 80x24 plus that extra line of function key labels:
https://en.wikipedia.org/wiki/IBM_BASIC#/media/File%3AIBM_Ca... (IBM BASIC screenshot)
Imagine when edit.com came out and QBASIC used it for the editor. You lost two more lines of valuable code space!
https://en.wikipedia.org/wiki/MS-DOS_Editor#/media/File%3AMS...
You know, this is funny because QBasic did not use EDIT.COM. Instead, QBasic was the editor and EDIT.COM was a simple program that called "QBASIC /EDIT" :-)
