Why the Apple II Didn't Support Lowercase Letters (2020)

Sometimes you only had upper case because the character generator was a 5*7 grid which wasn't really good enough to display lc.

5x7 is fine to display both lowercase and uppercase. You could even afford some stylistic variations!

Lack of ROM space for lowercase could be a more plausible explanation for an early computer.

You're probably right. There was a limitation to upper case only, I may misremember the cause.

Maybe interesting in this context: the CRT font renderers for the DEC PDP-1 (notably one of the first commercial machines for which a CRT was available) also rendered at 5 × 7 dots. (As bit patterns for 35 dots fit perfectly into two 18-bit words, with just one bit going unused.)

The first one, there's preserved source code, I would know of, was by Ben Gurley (the designer of the PDP-1) and Weldon Clark, April 10, 1961. [0] This one featured just upper-case letters, figures and the very minimum of special characters. Notably, the input devices used featured provisions for upper and lower case, hinting at the programmers wanting something workable done quickly. Moreover, the character set may not have defined fully, yet, since (reportedly) Ed Fredkin, then at BBN (and mostly responsible for BBN acquiring the first production prototype), was involved in the final definition.

Later, the same year, we also see a fully developed font renderer [1], which uses the spare bit in the glyph definition to indicate a drop of the entire font matrix, which enables drawing lower case characters with descenders. (This convention was also used by the later hardware symbol generator Type 33.) With this, all characters can be displayed with perfect readability (with possible compromises only involving lower-case "f".) At the same time, we also see support for the full character set, including representations of non-printable characters for editing.

[0] https://masswerk.at/spacewar/chargen/pdp1-bbn37-crt.html

[1] https://masswerk.at/spacewar/chargen/pdp1-1961-codeword-crt....

[2] Overview with links to related glyph dumps: https://masswerk.at/spacewar/chargen/

This article doesn't mention it explicitly, but the Apple II used the same character generator IC as the TV Typewriter, the Signetics 2513, with its 64-character ROM.