I hope this isn't too far off topic.

I am wondering about the history of lower case letters
in programming languages, and especially about case
sensitive languages.

The first I know about is C. Ones I knew before then
didn't allow then at all, though it might be that some DEC
compilers would ignore case.
[This is an interesting question. The IBM 7030 Stretch had
an upper/lower case character set, although I don't know how
much software used it. Algol60 was specified in lower case
but most implementations were upper case only. I can't think
of a language before C that was actually implemented in lower
case but I wouldn't count on it being the first. -John]

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On 10/11/2022 20:57, gah4 wrote:

I am wondering about the history of lower case letters
in programming languages, [...].
The first I know about is C. Ones I knew before then
didn't allow then at all, though it might be that some DEC
compilers would ignore case.

[John:]

[(...) Algol60 was specified in lower case
but most implementations were upper case only.

I think that's almost entirely down to the equipment available.
Eg, those of us who had Flexowriters [essentially electric typewriters
with paper tape facilities] expected to write programs in the same way
that we typed letters. Not just the programs, we were also early into
"word processing", and I remember the pleasure we got when someone
found out how to make the Flexowriter half space, so that it became
possible to "justify" lines without the jarring switch from single to
double spacing towards the end of most lines, but could instead go to one-and-a-half spacing. I also recall the culture shock when, around
four years later, I had my first encounter with punched cards, and had
to give up lower case, and with it most of the fun programming I was
[somewhat illicitly] doing.

I can't think
of a language before C that was actually implemented in lower
case but I wouldn't count on it being the first. -John]

Quite apart from Algol, Atlas Autocode was lower case. Keywords
were supposed to be underlined. However this was sufficiently tedious
that an upper case facility was quickly introduced, and most programs
[or programmes as we called them in those days in Rightpondia] started
with the [underlined] instruction "upper case delimiters". Underlining involved backspacing to the start of the word and going over it again
with the "_" characters, so was three times as much typing [and was also
very slow when printing].

--
Andy Walker, Nottingham.
Andy's music pages: www.cuboid.me.uk/andy/Music
Composer of the day: www.cuboid.me.uk/andy/Music/Composers/Schumann
[Oh, yeah, Flexowriters, where you did not want to put your coffee to the
left of one because the carriage will knock it over when it returns. I
used one with a Packard Bell (later Raytheon) 250 but I don't recall
any details of the input syntax for the languages it used. -John]

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On Saturday, November 12, 2022 at 4:22:00 AM UTC-8, Andy Walker wrote:

(snip)

Eg, those of us who had Flexowriters [essentially electric typewriters
with paper tape facilities] expected to write programs in the same way
that we typed letters. Not just the programs, we were also early into
"word processing", and I remember the pleasure we got when someone
found out how to make the Flexowriter half space, so that it became
possible to "justify" lines without the jarring switch from single to
double spacing towards the end of most lines, but could instead go to one-and-a-half spacing.

I used Wylbur and the IBM 2741 terminal pretty far back.

The 2741 uses the IBM Selectric typewriter as its print mechanism, so
is naturally lower case. Wylbur has a mode where all input data is converted to upper case (for programs), and a mode when it isn't (for letter writing).

Wylbur does have the justify command for letters, but no half spacing.

Systems I remember had the 1403 line printers set to map lower case
to upper case (except with the TN print train), which made it harder to
figure out when you got lower case into your programs or JCL.

As for C, it seems that predecessor B uses lower case for (reserved)
keywords. I don't see in the manual anything about the case of user identifiers, and especially if they are case sensitive.
[We used 2741 terminals with TSS/360 also. I think it did something
similar, normally mapping lower to upper case. -John]

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On Sunday, November 13, 2022 at 2:41:05 PM UTC-8, gah4 wrote:

(snip)

The 2741 uses the IBM Selectric typewriter as its print mechanism, so
is naturally lower case. Wylbur has a mode where all input data is converted to upper case (for programs), and a mode when it isn't (for letter writing).

(and our moderator noted)

[We used 2741 terminals with TSS/360 also. I think it did something
similar, normally mapping lower to upper case. -John]

The 2741 is interesting. It is not EBCDIC, but has a code based on the
way the Selectric typewriter works. Among others, the SHIFT key
rotates the ball 1/2 turn. The code has shift and unshift characters,
and then other characters depend on the current shift state.

And some systems, when they were otherwise too busy, send shift
and unshift about every second.

But I don't know what terminal K&R had at the time of C.
[They used a model 37 Teletype, which had upper and lower
case and ran at 15cps. They were not very common outside
of the Bell System iteslf. They also had model 33 and 35
which is why the early Unix tty drivers had a way to fake
lower case input. -John]

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