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