[TUHS] Curly braces: An evolution of UNIX and C

[Thalia Archibald via TUHS]

On Wednesday, May 20th, 2026 at 03:12, sjenkin wrote:
> Thalia,
> You've knocked it out of the park, again!
> 
> You posed a question I'd not even thought of. 
> [once used an ASR-33 on a Nova, then years using Telex in 1980's - same m/c ].
> 
> read your piece, excellent.
> 
> It took me ages to track down DMR's (?) list of tty's he'd used,
> only to find it was you that posted the note to TUHS.
> 
> That list might belong in the current article, as it provides some context.
> 
> Was it Dennis who wrote that list, because it doesn't include the ASR-33 attached to the PDP-7.
> 
> all my best
> steve j
> 
> ==============
> 
> Teletypes used for early Unix
> 21 Jul 2025
> <https://www.tuhs.org/pipermail/tuhs/2025-July/032302.html>
> 
> DMR's list of terminals
> <https://www.tuhs.org/pipermail/tuhs/2025-July/032332.html>

That's Dennis' list of personal terminals at home. I'd then consider the 1970
date for the Teletype Model 37 an approximate upper bound for when they started
using the Model 37 at work. Dereferencing to the post in alt.folklore.computers,
this could yield an even more precise date:

> It is true that word-processing and formatting (using Teletype model 37s) for
> the Bell Labs patent group was the first productive application of Unix
> outside our immediate group.

I had actually forgotten about that list. At the time I posted, I was looking
for the specific sub-model number of the Model 37s they were using, so it didn't
quite answer what I wanted. I already knew they were using the Model 37 and the
1970 date didn't help for that project. But it is useful for this post.


The sub-model configuration can be somewhat inferred through artifact analysis:

> - Two-color was optional

I don't recall seeing indication of red color use. I'll have to look further.

> - The shift-out character set was configurable

UNIX has Greek SO/SI character tables and Dennis_Tapes has a directory named
<SO>J<SI> for pi.

> - An ASR could come without a tape reader/puncher

I don't know what I meant by this; that's just a KSR. I'd think I'd've known
that, but perhaps I'm referring to something else.

> - Half-line forward and reverse was optional
> - Character sizes varied, e.g., 72 chars per line at 10 chars per inch,
>   adjustable up to 80 per line; or 86 per line at 12 per inch

They used half-forward and -reverse line feeds for sub- and superscripts in the
UNIX "V0" mid-1971 manual that was printed by a 37. This document has 65
characters per line, though probably with artificial margins. I could determine
the character size by measuring it.

> - The paper could be roll paper (friction feed)or flat-folded, form-feed paper
>   with marginal perforations (sprocket feed)

At VCF 2025, Brian Kernighan said they used fan fold, and sprocket feed was more
common, in my experience.

> - Paper sizes varied, e.g., 3 to 8-1/2 wide or, for sprocket feed, up to 11
>   inches long and 9-1/2 wide

My Model 43s use 12" wide x 8x5" long paper. It's landscape 8x5"x11", but with
0.5" sprocket perforations. Perhaps that what the 11" means, but I'm sure my
sources would make it clear. I would expect they'd've used the widest option.

But the mid-1971 manual is regular letter sheets, not continuous or perforated.
The perforated edges could have been removed and they could be cut apart. Given
that the patent group was using the 37, presumably also for letter or legal
output, I think it's reasonable to say this still used a 37, since it uses
somewhat exotic features of that model (half-forward and -reverse).

> - Some printed control characters; most didn’t

I doubt they had a character set for printed control characters. We'd think of
control characters differently now, if they were routinely printed.

> - Holding a key could be configured to repeat the character

No idea. This one couldn't be determined through source analysis. Probably only
a niche case like a game requiring character repetition for some control.

I figure they used the default set of repeating characters. It's a strange set
of characters:
    space, NEW LINE, BACKSPACE, NULL, DELETE, period ., hyphen - or equals =,
    underscore _, colon : or asterisk *, upper case X or lower case x
    https://github.com/thaliaarchi/tty37-docs/blob/main/tty37.md#character-repeat-feature

> - They could operate half-duplex (transmitted data is copied by the sender) or
>   full-duplex (only received data is copied)

UNIX was half-duplex so passwords weren't echoed.

> - They could receive and transmit at various speeds

They probably used the default of 150 baud.

Additionally:

They used 8-space tabs. I don't know of vertical tab usage, but sources may
indicate.


Thalia