Summary of LOGGING INTO LINUX WITH A 1930S TELETYPE
This article details [CuriousMarc]'s project connecting a 1930s Model 15 Teletype to Linux. The challenge involved bridging the gap between the obsolete five-bit Baudot code and modern ASCII using an Arduino Mega as a converter. Additionally, custom hardware was required to adapt the Teletype's high-voltage 60-mA current loop interface for computer use. After testing with a Hewlett-Packard signal generator, Marc successfully logged into Linux via the vintage terminal at a slow 45.5 bps rate.
Parts used in the Model 15 Teletype Restoration:
- Model 15 Teletype
- Arduino Mega
- Custom hardware for 60-mA current loop interface
- Hewlett-Packard serial signal generator
- Modern machine running Linux
Buried deep within all UNIX-based operating systems are vestiges of the earliest days of computing, when “hardware” more often than not meant actual mechanical devices with cams and levers and pulleys and grease. But just because UNIX, and by extension Linux, once supported mechanical terminals doesn’t mean that getting a teletype from the 1930s to work with it is easy.
Such was the lesson learned by [CuriousMarc] with his recently restored Model 15 Teletype; we covered a similar Model 19 restoration that he tackled. The essential problem is that the five-bit Baudot code that they speak predates the development of ASCII by several decades, making a converter necessary. A task like that is a perfect job for an Arduino — [Marc] put a Mega to work on that — but the interface of the Teletype proved a bit more challenging. Designed to connect two or more units together over phone lines, the high-voltage 60-mA current loop interface required some custom hardware. The testing process was fascinating, depending as it did on an old Hewlett-Packard serial signal generator to throw out a stream of five-bit serial pulses.
The big moment came when he used the Teletype to log into Linux on a (more or less) modern machine. After sorting out the mysteries of the stty command, he was able to log in, a painfully slow process at 45.5 bps but still a most satisfying hack. The ASCII art — or is it Baudot art? — is a nice bonus.
We love restorations like these, and can practically smell the grease and the faint tang of ozone around this device. We’re not thrilled by the current world situation, but we’re glad [CuriousMarc] was able to use the time to bring off a great hack that honors another piece of our computing history.
Source: LOGGING INTO LINUX WITH A 1930S TELETYPE
- Why is connecting a 1930s teletype to Linux difficult?
The five-bit Baudot code predates ASCII by decades, requiring a converter. - What microcontroller did CuriousMarc use for the conversion task?
An Arduino Mega was used to handle the data conversion. - What specific interface challenge did the teletype present?
The device uses a high-voltage 60-mA current loop interface designed for phone lines. - How was the project tested before connecting to Linux?
Testing relied on an old Hewlett-Packard serial signal generator to send five-bit pulses. - What command was adjusted to allow logging in?
The stty command mysteries had to be sorted out to enable login. - At what speed does the teletype communicate with the modern machine?
The process runs painfully slowly at 45.5 bps. - Does the restored teletype produce visual output similar to ASCII art?
Yes, it produces Baudot art as a bonus feature.
