[TUHS] Teletypes used for early Unix

[TUHS] Teletypes used for early Unix

[Thalia Archibald via TUHS]

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Hello all,

What teleprinter models were used at Bell Labs, particularly by the Unix groups? Judging by troff escape sequences, it expected a Teletype Model 37, and early all-caps support implies Model 33 usage. But I don’t have a sense of what users and the core developers used.

I am working on building a Teletype Model 37 ASR emulator for my PiDP-11 with the goal of replicating the early Unix experience as accurately as possible without physical hardware.

As I get deeper into research, I’ve learned of a variety of configuration options beyond what the operator could configure with buttons, e.g., sub-models which come with different components, optional components which can be installed later, and features that can be configured by a craftsman. Here are some examples:

- Two-color was optional
- The shift-out character set was configurable
- An ASR could come without a tape reader/puncher
- 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
- The paper could be roll paper (friction feed)or flat-folded, form-feed paper with marginal perforations (sprocket feed)
- 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
- Some printed control characters; most didn’t
- Holding a key could be configured to repeat the character
- They could operate half-duplex (transmitted data is copied by the sender) or full-duplex (only received data is copied)
- They could receive and transmit at various speeds

That’s a lot of options and it’s not exhaustive.

The Model 37 product catalog[0] has tables of many configurations and their catalog numbers. Is there a list of the teleprinters purchased by Bell Labs? With that, I could possibly narrow it down like how Warner Losh identified the PDP-7 model used for Unix V0.

Thanks!
Thalia Archibald

[0]: https://ia800702.us.archive.org/32/items/TNM_Model_37_terminal_product_catalog_-_Teletype__20170923_0036/TNM_Model_37_terminal_product_catalog_-_Teletype__20170923_0036.pdf
[1]: https://bsdimp.blogspot.com/2019/07/the-pdp-7-where-unix-began.html

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[TUHS] Re: Teletypes used for early Unix

[Dave Horsfall]

On Mon, 21 Jul 2025, Thalia Archibald via TUHS wrote:

[...]

> I am working on building a Teletype Model 37 ASR emulator for my PiDP-11 
> with the goal of replicating the early Unix experience as accurately as 
> possible without physical hardware.

The fount of all wisdom and knowledge on Teletypes would be the 
"Greenkeys" mailing list, over at

    List-Id: "Discussion of older radio teletype (RTTY) gear "<greenkeys.mailman.qth.net>"

It's RTTY (Radio Teletype) related i.e. "ham" radio, but there's a lot of 
knowledge over there.

-- Dave

[TUHS] Re: Teletypes used for early Unix

[Jonathan Gray]

On Mon, Jul 21, 2025 at 01:44:26AM +0000, Thalia Archibald via TUHS wrote:
> 
> The Model 37 product catalog[0] has tables of many configurations and their catalog numbers. Is there a list of the teleprinters purchased by Bell Labs? With that, I could possibly narrow it down like how Warner Losh identified the PDP-7 model used for Unix V0.

Not quite what you are asking, Dennis Ritchie provided a list of
terminals he used at home.

From alt.folklore.computers Jan 13, 1993
https://groups.google.com/g/alt.folklore.computers/c/qwI7XHPBu-s/m/NgGcn_SibNQJ

"for the sake of history, here is the sequence of terminals I have used
at home, all paid for by my employer. Dates are approximate.

1968: IBM 1050 (14.5 cps)
1970: Teletype 37 (15 cps)
1975: GE Terminet 300 (30 cps)
1978: HP 2621 (120 cps)
1983: Jerq (Blit) (120, later 960 cps)
1990: Gnot (Plan 9) (960 cps)
1992: Gnot (Plan 9) (8192 cps ISDN)"

When John Lions was at Bell Labs on sabbatical:

"Up till now I have been using a tty 43 (this listing)
...
there is a noticeable preponderance of hard copy and lack of CRT terminals."
John Lions, 15 August 1978
AUUGN Vol 1, No 1, p 21

from Dennis Ritchie in alt.folklore.computers Feb 12, 2011
https://groups.google.com/g/alt.folklore.computers/c/TbnWa4H0qS0/m/RUFInaTmgIwJ

"Unix in 1969 was mostly written on a TTY33. Our PDP-7 also had a
full-ASCII keyboard that was part of the locally-built Graphics-II
processor attached to the PDP-7, used for Space Travel, for example,
and also for development once Unix was self-supporting."

Dennis mentions an ASR33 for the initial PDP-11 in:
https://www.tuhs.org/pipermail/tuhs/2002-September/002162.html
https://www.tuhs.org/pipermail/tuhs/2002-September/002181.html

More terminal discussions from alt.folklore.computers:
Oct 31, 2001
https://groups.google.com/g/alt.folklore.computers/c/2hIR4udbSD0/m/peXf7MB75IMJ

May 10, 2005
https://groups.google.com/g/alt.folklore.computers/c/yUlJLKto-LQ/m/0la-n5KCxdMJ
on the IBM 2741 as used with CTSS and Multics

[TUHS] Re: Teletypes used for early Unix

[Ron Natalie]

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At Hopkins we had a KSR37 which had the big ol’ NEWLINE key and did 
stuff with the ESC 8 and 9 stuff that nroff spewed directly.   It even 
had a greek box that was well integrated into eqn.

It largely got supplanted with the faster and nicer printing diablo and 
even that fell to the versatec troff emulators and eventually to things 
like the Imagen laser printers.

I procured my own Model 37 from the Rocky Flats Nuclear Site surplus 
department.   It had a big sidecar paper tape punch reader.

-Ron

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[TUHS] Re: Teletypes used for early Unix

[Larry McVoy]

On Wed, Jul 30, 2025 at 10:27:23AM +1000, Jonathan Gray wrote:
> "The remote-batch load absorbs about 5 per cent of the 11/70 and its
> residual capacity is used to serve nearly 50 interactive terminals.

I still remember, fondly (sort of) being in a terminal room with 50+
other students all hooked up to a 4MB VAX 780.  The fondness was the
sort of bonding we all had from pulling all nighters to get stuff to
work (this was at UW-Madison, back then it was a hard core hacking
school, lots of Sun's kernel group came from Madison, including 
Rusty (NFS) and Mojo (he wrote the 4.x VM system) and a bunch of 
others).

The not so fond part was hit ^T over and over again (it gave you
a one line PS like output showing load) while your compiled seemed
swapped out forever.

The not fondness made me take out one of the very few loans I have had,
in 1985ish I borrowed $2000 to buy a Okidata CPM machine, it was a lot
slower than the VAX, but all the cycles were mine.  I wrote a lot of
code on that machine.  Including assembler versions of cp, rm, ls, 
etc, each of which fit in 512 bytes because that was one sector on
a floppy disk, I didn't want to wait for more than one sector to 
load.  Fun times.  Now my phone is like 10,000x faster and has 
easily that much more memory.

--lm

[TUHS] Re: Teletypes used for early Unix

[segaloco via TUHS]

On Tuesday, July 29th, 2025 at 6:15 PM, Larry McVoy <lm@mcvoy.com> wrote:

> On Wed, Jul 30, 2025 at 10:27:23AM +1000, Jonathan Gray wrote:
> 
> > "The remote-batch load absorbs about 5 per cent of the 11/70 and its
> > residual capacity is used to serve nearly 50 interactive terminals.
> 
> 
> I still remember, fondly (sort of) being in a terminal room with 50+
> other students all hooked up to a 4MB VAX 780. The fondness was the
> sort of bonding we all had from pulling all nighters to get stuff to
> work (this was at UW-Madison, back then it was a hard core hacking
> school, lots of Sun's kernel group came from Madison, including
> Rusty (NFS) and Mojo (he wrote the 4.x VM system) and a bunch of
> others).
> 
> The not so fond part was hit ^T over and over again (it gave you
> a one line PS like output showing load) while your compiled seemed
> swapped out forever.
> 
> The not fondness made me take out one of the very few loans I have had,
> in 1985ish I borrowed $2000 to buy a Okidata CPM machine, it was a lot
> slower than the VAX, but all the cycles were mine. I wrote a lot of
> code on that machine. Including assembler versions of cp, rm, ls,
> etc, each of which fit in 512 bytes because that was one sector on
> a floppy disk, I didn't want to wait for more than one sector to
> load. Fun times. Now my phone is like 10,000x faster and has
> easily that much more memory.
> 
> --lm

Larry if you don't mind my curiosity, were these UNIX-y utilities sitting on top of and using CP/M services or chomping at the hardware a little more closely?  Or something else?

- Matt G.

[TUHS] Re: greenbar fanfold paper - anyone else miss it?

[segaloco via TUHS]

On Tuesday, July 29th, 2025 at 11:02 PM, arnold@skeeve.com <arnold@skeeve.com> wrote:

> Douglas McIlroy douglas.mcilroy@dartmouth.edu wrote:
> 
> > An extant memento of my home TTY 37 is a stack of fanfold paper that
> > accommodated artwork by children and grandchildren. About 1/4".remains
> > for potential great-grandchildren.
> > 
> > Doug
> 
> 
> I really miss 11" x 17" greenbar fanfold paper. It was wonderful
> for printing out program listings and reviewing code. One could
> make notes on the side of the code, flip back and forth between
> different files to see how different data structures were used,
> and so on. It was great.
> 
> That's how I first learned the gawk code (MUCH smaller at the
> time). I printed out the whole thing and read through it, making
> notes.
> 
> Sigh. The good old days.
> 
> Arnold
> 
> P.S. Some years ago I went through the binders on my bookshelves to
> get rid of things. From that I have a stack about 4 feet high of letter
> paper printed one-sided on a laser printer, waiting for use by future
> grandchildren. Sadly, not one of my kids is married. (These days my
> laser printer does duplex; anything I don't need goes into recycling.)
> 
> Whatever. We now return you to our regularly scheduled reminiscing.

Getting COFFy but TUHS bcc, I intend for an upcoming software analysis project to print paper copies and comb over things very finely with a pen.  The project is a thorough Lions-esque analysis of Super Mario Bros. 3 for the Famicom/NES.  I hope once I'm "done" with my disassembly of it to first print a full copy to sit at coffee shops with and annotate and then eventually produce something comparable to the Lions' publication but the SMB3 code and an accompanying commentary (typeset with troff of course).  How grand it would be to have the printouts on true terminal fan-fold.

Recently I did spot a Ti hardcopy terminal sitting in a junk pile at the university, I am forever kicking myself for not grabbing it...it did use some sort of continuous paper, but looked to have a reel rather than fan-fold uptake, I didn't make note of the model, only that it had a typical DB-25 (presumably RS-232) serial jack.  Granted if I'm simply printing for analysis waiting for a terminal to print it is overkill...

- Matt G.