8 ms·

Initially because teletypes only had uppercase, and those were the only tty devices available. And then when early CRT terminals became available, RAM was expe

Initially because teletypes only had uppercase, and those were the only tty devices available. And then when early CRT terminals became available, RAM was expensive, and you could save a whole chip by not storing one more bit per screen character.

tgv 3y ago
I think it's from even earlier. IIRC, the first punch cards didn't distinguish between upper and lower case. These were used for basic administration, so one case was enough. E.g. https://en.wikipedia.org/wiki/Punched_card#IBM_80-column_format_and_character_codes https://en.wikipedia.org/wiki/Punched_card#IBM_80-column_for...
- nemo 3y ago
  Teleprinters/teletypes go back further than you think. The first were in the 1800s. By the early 1900s teletypes had already become standardized around the time IBM developed the 80-column punchcard.
- mtreis86 3y ago
  Baudot predates both and doesn't have caps
- retrac 3y ago
  I think paper tape and teletypes predate punchcards for IT applications. Baudot's work started in the 1870s, and fully automatic teleprinter systems were in operation by the 1900s (decade) [1]. IBM may not have been punching alphanumeric content until the 1920s (as your article suggests)? Baudot (the code, not the man) was 5 bits, so only 32 codes. It couldn't even fully encode the alphabet and the digits; shift codes are used to switch between two sets of symbols. Lowercase was added quite early though. Some hot metal casting typesetting machines ran on paper tape. They typically used six bit codes with multiple sets of shift cases. Upper, lower, digit, symbol, etc. (The physical construction of the teleprinter or typesetter had some relation to the nature of the code used.) The use of paper tape decoupled typesetting from the work of preparing and laying out the physical plate for printing. Typesetter and printer could be in different rooms or buildings, or maybe even on different continents; those tapes were being run over telegraph circuits by the late 1920s. [1] https://en.wikipedia.org/wiki/Baudot_code#Murray_code https://en.wikipedia.org/wiki/Baudot_code#Murray_code
  - jasomill 3y ago
    As a concrete example of what you're describing, here's an example of a code used with Linotype typesetting machines: https://archive.org/details/LinotypeHandbookForTeletypesetterOperation1951/page/n18/mode/1up https://archive.org/details/LinotypeHandbookForTeletypesette... This code contains two shift states which map directly to physical Linotype features: 1. Shift and Unshift states map the first 45 codes to the 90 character positions in a standard Linotype magazine. 2. Some Linotype matrices (letter molds) have two font variants (e.g., roman and italic); the UR and LR codes shift between these.
kstrauser 3y ago
The link goes on to answer the questions, but without it I'd ask: So why, then, were teletypes only uppercase instead of only lowercase?
- jlawson 3y ago
  Probably because uppercase letters generally look better monospaced without descenders.
kelnos 3y ago
Your answer doesn't actually get deep enough. You say "because teletypes only had uppercase" -- but there is still a "why?" there -- they could have only had lowercase instead. The article answers this in a more comprehensive way by examining the history of typesetting and written script.

tgv 3y ago

I think it's from even earlier. IIRC, the first punch cards didn't distinguish between upper and lower case. These were used for basic administration, so one case was enough. E.g. https://en.wikipedia.org/wiki/Punched_card#IBM_80-column_format_and_character_codes https://en.wikipedia.org/wiki/Punched_card#IBM_80-column_for...

nemo 3y ago
Teleprinters/teletypes go back further than you think. The first were in the 1800s. By the early 1900s teletypes had already become standardized around the time IBM developed the 80-column punchcard.
mtreis86 3y ago
Baudot predates both and doesn't have caps
retrac 3y ago
I think paper tape and teletypes predate punchcards for IT applications. Baudot's work started in the 1870s, and fully automatic teleprinter systems were in operation by the 1900s (decade) [1]. IBM may not have been punching alphanumeric content until the 1920s (as your article suggests)? Baudot (the code, not the man) was 5 bits, so only 32 codes. It couldn't even fully encode the alphabet and the digits; shift codes are used to switch between two sets of symbols. Lowercase was added quite early though. Some hot metal casting typesetting machines ran on paper tape. They typically used six bit codes with multiple sets of shift cases. Upper, lower, digit, symbol, etc. (The physical construction of the teleprinter or typesetter had some relation to the nature of the code used.) The use of paper tape decoupled typesetting from the work of preparing and laying out the physical plate for printing. Typesetter and printer could be in different rooms or buildings, or maybe even on different continents; those tapes were being run over telegraph circuits by the late 1920s. [1] https://en.wikipedia.org/wiki/Baudot_code#Murray_code https://en.wikipedia.org/wiki/Baudot_code#Murray_code
- jasomill 3y ago
  As a concrete example of what you're describing, here's an example of a code used with Linotype typesetting machines: https://archive.org/details/LinotypeHandbookForTeletypesetterOperation1951/page/n18/mode/1up https://archive.org/details/LinotypeHandbookForTeletypesette... This code contains two shift states which map directly to physical Linotype features: 1. Shift and Unshift states map the first 45 codes to the 90 character positions in a standard Linotype magazine. 2. Some Linotype matrices (letter molds) have two font variants (e.g., roman and italic); the UR and LR codes shift between these.

kstrauser 3y ago

The link goes on to answer the questions, but without it I'd ask: So why, then, were teletypes only uppercase instead of only lowercase?

jlawson 3y ago
Probably because uppercase letters generally look better monospaced without descenders.

kelnos 3y ago

Your answer doesn't actually get deep enough. You say "because teletypes only had uppercase" -- but there is still a "why?" there -- they could have only had lowercase instead. The article answers this in a more comprehensive way by examining the history of typesetting and written script.