[duskwuff]

I can confirm that. On the TI-83, many of the TI-BASIC tokens contained lowercase characters which couldn't be typed at all - you could only type uppercase letters on the keyboard. (There were a few lowercase letters available as tokens for special purposes, but it wasn't a full set.)

Interestingly, you could print tokens in strings - e.g. you could Disp "Disp ".

[suburban_strike]

The 83+ let you type the full set of lowerchase chars as well, but they used 2x as many bytes per character for storage.

[7jjjjjjj]

There's actually a hidden lowercase feature, you can use an assembly program to enable it.