With temps in the high 90s and low 100s in Philly, after picking up my Teletype ASR-32 a week ago, I’ve been sitting in the AC diving into all sorts of resources, web sites, and videos learning about them and the various technologies they either originally used or continue to use today.
A History Lesson
The first thing a lot of people find when messing with technology they’re not familiar with is learning the lingo; reading forum posts, old magazines, manuals, etc you tend to find that it reads like another language. In this case I found teletype technologies in general seem to have a lot of “alternate” names. For example, the model teletype I have is a 5-bit model that talks in “BAUDOT” as opposed to ASCII. While it does the full aphabet and numbers 0-9, only a limited set of punctuation and symbols are supported, and letters are supported only in uppercase. BAUDOT can also be represented as ITA2, or Murray Code*, or if speaking in amateur radio, RTTY.
*Speaking technically, BAUDOT itself was ITA1 (international alphabet 1)…the version most teletypes use is the “Murray Code” or ITA2, which was a modification of the “original” BAUDOT code, so while the terms all generally refer to the same thing, there was an older/original version dating back to the 1800s, and a newer version that was ultimately used for years with Teletype technology.
I also learned about how they connected both back in the day, such as the TWX/Telex services, and press/news agencies like Associated Press and UPI and how they can continue to be utilized today (RTTY, ITTY, and use with (vintage) computers). In terms of Telex and TWX there were some interesting reads there, although I haven’t really found a solid technological explanation as to how the actual Telex lines worked, and if they can be “emulated” today, other than a german project where the web site is unfortunately in german. It did seem like Telex lines were generally not much different from POTS, and in once article I did see that they were different enough that a pots phone could not work/use/call a Telex line.
Update 8-22-2021; a LOT more reading and learning since I originally posted this, and here’s the quick version: “TELEX” was originally the Western Union system, and used “loop” circuits (aka literal Telegraph lines). While TELEX machines have a dial, its not for calling on a standard PSTN line; it was a system all to itself.
TWX on the other hand, later on used standard PSTN/POTS lines (also called DDD I learned), and later in it’s life, was simply a “dataset” or modem built into the base of the Teletype. Particular to how the lines worked, TWX generally used standard phone lines, but they were blocked at ma-bell from calling regular voice numbers (TWX had their own area codes). Also, there was equipment at MA Bell that allowed a Telex to call a TWX and vice-versa, having to do both a line and speed conversion in order to make it happen.
I also learned that these baudot machines run at 45.5 baud, 5 data bits, and 1.5 stop bits.
Another interesting rabbit hole came from the front plate on the unit itself, which reads “Carterfone Communications”. While in this case, “Carterfone Communications” likely refers to a dealer of teletype equipment, the Carterfone company (not sure if any relation to this dealer) had a monumental influence on telecommunications in its epic win against ma bell. I may have to do a separate post on that sometime.
Last but not least, I learned about how teletype technology was eventually used to automate the printing industry via the Linotype machines. These incredible machines were almost fully automatic and created lead-based printing slugs (a line of text) by typesetting, and molding them. While they were mostly manual at first, later they used the same paper tape that stored the articles from the news services to convert the downloaded article directly into lines of type to be used to print books and newspapers. This old but excellent video really explains how these amazing machines work, and touches on the paper tape aspect of it towards the end. Its a longer video but worth watching if you’re into this stuff…
Getting Started
While there are a ton of web sites out there, both new and old in terms of helping one get a Teletype running, I found a few out of the gate that helped. Bill Degnan’s VintageComputer.net site really helped (and Bill and others have done a number of talks about Teletypes at VCF East), and this page also had some great info and things to look for as well https://www.bytecollector.com/asr_33.htm. Rtty.com has tons of info about radio-teletype as well as an internet-based rtty audio stream called ITTY, providing a way to let hobbyists let their machines sing without needing radio equipment (you still need a RTTY decoder though).
Next, I’m putting this in bold as it took me a while to find this nugget of information:
IF YOU DO NOT HAVE A CURRENT LOOP, THE MACHINE WILL JUST RUN.
Again, knowing very little about a “real” teletype with a current loop connection, if you do not have a proper loop or the machine is simply not hooked up to anything, it will just sit there and chug-chug-chug away with no response from the keyboard or punch tape. This is NORMAL, and while I’m not sure if the current loop can simply be shorted on it for testing purposes, you really need to connect it to something to test it out.
Lastly, having the manual to your particular machine is very helpful in terms of connections and being able to service the unit. These things are often 50+ years old now and with many of them sitting idle for years, dried grease, dust and other things haven’t been their friend. It’s also very important that before your machine gets used, to check the rubber hammer on the ASR 32/33. If this is missing or goo, it can potentially destroy your (unobtainium) print head.
Moving Along…
Moving along, after a ton of reading, I was able to reverse-engineer the connections the previous owner did, and connected my Teletype to the HAL ST-6 decoder. (Previous owner really labeled things well so in this rare case it was fairly easy, after checking out some things for safety reasons). Once connected, the machine stopped “chugging” and now worked as a typewriter. I was able to type things onto the paper, and even fiddled with the paper tape reader to both read and type to tape. While my machine likely needs some love in terms of maintenance and lubrication, I think it was well taken care of and seems to be working ok as-is.
My next test was to plug an old ipad into the audio input of the HAL ST-6, and try streaming the ITTY stream (linked above) to it, which actually worked! One thing to note is that the ITTY service has 3 streams (as of this writing) – the first is a non-stop 24/7 stream of news and user-submitted article, the second is a European stream, and the third is an “auto-start” stream that only streams content a few times a day. Note that the European stream uses a different baud rate and likely won’t work with an older BAUDOT based Teletype.
One fun goal I have is to perhaps let it do a re-print of the original moon landing bulletins, which I should be able to do simply using a computer and FLDIGI to stream the rtty signal over to the HAL. This week marked the 50th anniversary of the moon landing. It actually took me quite a while, but I found the content for the UPI bulletins here: https://sci.space.history.narkive.com/SfoyCfPu/upi-wire-copy-for-a11-landing
Last but not least, I found a local junk shop that had 2 boxes of 11/16″ paper tape* for the unit, which was an awesome find, however when I got home and looked at the box of stuff that came with it, I found the previous owner included a case of tape as it was, so I have a LOT, likely a LIFETIME supply of paper tape LOL.
** Paper tape generally comes in 2 sizes – 5-bit baudot tape is 11/16″, and 8-bit tape typically used by the ASR-33 and vintage computers was 1″ tape.
Anyhow after letting it print a couple articles, I shut it down and organized everything for the eventual trip out of my basement/ground floor up to my office where I can do more with it later on, both with some computers as well as on the air.
Stay tuned for more Teletype adventures!