HN Theater @HNTheaterMonth

I can second CuriousMarc and Ben Eater for anyone interested in computer engineering.

CuriousMarc has an amazing series on the Apollo Guidance Computer, as well as great one-off videos like running a linux terminal on a teletype (https://youtu.be/2XLZ4Z8LpEE).

Ben Eater does amazing videos on low level electronics, and has a great series on understanding how a computer really works.

> The client sends l and then immediately receives an l sent back. I guess the idea here is that the client is really dumb – it doesn’t know that when I type an l, I want an l to be echoed back to the screen. It has to be told explicitly by the server process to display it.

Of course the client may be really dumb! Here is a 1930s teletype used as a Linux terminal:

https://youtu.be/2XLZ4Z8LpEE?t=656

If you would not do it that way, you would run into all kinds of synchronicity problems. How could you be sure that, after rapidly making 50 keystrokes, every keystroke was received by the other end, in that order?

⬐ gnubison

More importantly, how do you know whether the keystrokes should be displayed at all? For example, take vi. When it starts up, it sets cc.c_lflag &= ~ECHO (basically like “stty -echo”) so that normal mode commands aren’t printed onscreen. The kernel knows whether ECHO is set, which is why it handles echoing.

⬐ icedchai

This was definitely a problem in the dialup modem days before error correction, where line noise might add extra characters, or modify what you were sending.

⬐ freedomben

> How could you be sure that, after rapidly making 50 keystrokes, every keystroke was received by the other end, in that order?

Exactly. I implemented a client that emulated a VT100 early in my career, and this is a real problem. There are various strategies you can use but by far the simplest and safest seemed to just be the echo and for the client to always display exactly what it receives[1].

There's nothing worse than typing out a command that you realize is wrong and potentially destructive, only to Ctrl+U it and have the client kill the line but the server didn't get the instruction, so when you press enter it runs the evil command. If the command doesn't echo anything you may not even know! I once accidented a space in the path I was deleting when (recklessly with -rf) trying to remove my ~/bin directory, like this:

    rm -rf ~ /bin

Good Lord that was a bad day. Thankfully I still had the installation disc to restore /bin, and a relatively recent backup of my home directory to restore that. I lost a few days of uncommitted code, but that felt like a trifle compared to what it could have been :-)

[1]: I love how mosh[2] handles this to get the best of both worlds. It will smartly show you what you typed, but sill underline it until it actually receives the echo from the server, so you can type and feel like there's no delay between bytes, but still be confident that client state matches the server state.

[2]: https://mosh.org/

A few recommendations from an avid armchair computer historian:

- Dealers of Lightning is a wonderful book covering Xerox PARC's history and contributions. If you don't know what Xerox PARC is, then you should definitely read it.

- Where Wizards Stay Up Late is a highly-readable, engaging book covering the history of the Internet's early development.

- Soul of a New Machine gives a compelling glimpse into the era when physical machines and unique architectures were more dominant than software in shaping the market.

- The Jargon File as maintained by Eric Raymond is not without controversy, but I think it's still fair to say a lot of computing folklore and cultural history is preserved there. http://www.catb.org/jargon/html/index.html

- Folklore.org is a wonderful, wistful collection of stories from the early days of Apple Computer, as told by some of the engineers and programmers who made it what it was in the 80s and early 90s.

- The Thrilling Adventures of Lovelace And Babbage is a wonderful graphic novel that's full of utterly ridiculous fiction that's only loosely inspired by the title characters. However, it is jam-packed with footnotes about the actual history from top to bottom, and in my opinion, there probably isn't a better or more fascinating glimpse of the proto-history of the computer anywhere.

- Douglas Engelbart's Mother Of All Demos is well worth watching (can be found on YouTube), and maybe reading some commentary on. Mind-blowing what his team put together that we still haven't really matched in some ways.

- Vannevar Bush's piece "As We May Think" isn't really about computers, but it's hard not to connect it to them when you read it. And then maybe to sigh and wonder how someone who didn't have any machine like what he describes can have a vision more compelling than what we've actually managed to build, so many decades before it happened.

- If you're interested in hypertext, look into Ted Nelson. None of his work ever really took off, and Project Xanadu was a legendary mishandled undertaking, but his vision for what might have been is fascinating, and influenced many of the software pioneers, as I understand it.

- This glorious video of using a 1930s teletype as a command-line Linux terminal taught me a surprising amount about why the classic Unix tools work as they do. https://www.youtube.com/watch?v=2XLZ4Z8LpEE

Enjoy!

⬐ dddw

love this. Was it running crunchbang??

⬐ bradknowles

On occasion, when I was first studying CS back in the mid-80s, our Engineering Computer Network lab would have all the glass ttys (vt100, etc…) occupied, and if I wanted to get any work done, then I’d have to log in at the hard-copy teletype and use programs like ‘xed’ instead of ‘vi’ to edit my code.

I don’t recommend it.

If you haven't seen it before, you might enjoy this: https://youtu.be/2XLZ4Z8LpEE (Using a 1930 Teletype as a Linux Terminal).

⬐ z2

Watching him use ED on the teletype, the lack of ED's interactivity and terseness suddenly makes sense! Though obvious now, it never occurred to me that the tool was designed around physical printing interfaces.

⬐ retrac

All of UNIX was. Right down to the decision for commands like cp (not copy!) to not print anything unless there's an error. A decade later MS-DOS could be profligate and waste virtual ink printing friendly messages like "2 file(s) copied."

⬐ taylorfinley

I recently picked up a couple deaf tty terminals[0] for free from a local junk shop. They have a bright green vfd display and print to a roll of thermal paper, they feature a big acoustic coupler on the top for a phone handset and have a nice physical keyboard. My plan is to record the tones for each letter, then rig up a pi as a serial-to-audio adapter with a cheap 'retro phone handset to 3.5mm plug' product that can easily be found for ~$10 in the usual places. I can leave the original hardware intact and have a fun terminal. [0] https://teltex.com/ultratec-miniprint-425/

⬐ gnulinux

This is like exactly what I imagined... I'll study this and see if this is something I can do in a few weekends (the answer is likely no as I don't have a lot of hands-on engineering experience, just basics of EE and soldering). Is there any consumer product like this (not necessarily typewriter, e-ink or dumb display would also be ok; I just don't want a full-fledged display that can print images).

Computer distraction is killing my life and I'm currently spending Saturdays as no-screen day (no phone/computer use) but I'd be willing to use a calculator-on-steroids like this as a replacement, which I imagine is not as distracting. (Usual TI programmable calculators are what I'm eyeing right now but their keyboard is not good. I want a usual Qwerty keyboard and linux)

⬐ TedDoesntTalk

I don’t think you can build this in a few weekends, assuming you can even get all the parts in that time.

I would instead get a dumb terminal from eBay from the 70s or 80s (search “terminal” or “televideo” for one of the brand names) and hook it up to a raspberry pi via rs-232. There are several projects on the web showing how to do this (hint: getty on linux)

No graphics and video, but you get a good keyboard and solid ascii output.

Going by the scenario in the first paragraph 1930 might be your answer. Here is a video of a 1930 teletype connected to a linux machine:

https://www.youtube.com/watch?v=2XLZ4Z8LpEE

To really understand how ed was useful, it's eye-opening to see exactly what life was like before video terminals.

Essentially, think of using your laptop, but instead of looking at a monitor you're reading the output from a printer. So if you type `ls`, you see the directory listing being literally printed out on a dot-matrix printer. Naturally the only way of text editing is with a line EDitor, which lets you edit text one command at a time.

When trying to use ed on a video terminal, it obviously looks wasteful. But that's because it was designed before video terminals were a thing. Kind of like using a modern day graphics card to play pong.

here is a video illustrating using a teletype:

https://www.youtube.com/watch?v=2XLZ4Z8LpEE

⬐ as_keyof_typeof

Wow, that is a fascinating video and such an inspiring spirit of hacking. I'd love to learn more about the electrical engineering side of computer science to be able to do similar experiments.

I've linked this before, but this video of hooking a 1930s teletype up to a Linux computer is what made ed click for me.

https://www.youtube.com/watch?v=2XLZ4Z8LpEE

It's one of the best things on the Internet, IMO.

⬐ coldpie

Along the same lines, this series of videos is one of my favorite things I've run across recently: https://www.youtube.com/watch?v=suyiMfzmZKs&list=PLB3mwSROoJ...

It starts with using the front panel switches to load a program into an Altair 8800 and progresses into loading programs from external sources including audio cassette and paper tape; loading programs from a ROM; loading and using an OS; and using a paper terminal for output.

⬐ lqet

Very cool indeed. The usage of ed starts here:

https://youtu.be/2XLZ4Z8LpEE?t=818

⬐ russh

The Model 23 Teletype connected to my Netronics ELF II was so loud I was only allowed to use it during the day. It was slow, noisy and smelled like a mixture light Oil and electrical sparks but you could play Tiny Star Trek on it. At least until sundown, or it ran out of paper.

Perhaps my favorite video on YouTube is this glorious footage of someone hooking a 1930s teletype up to a computer running Linux:

https://m.youtube.com/watch?v=2XLZ4Z8LpEE

Watching it for the first time is what finally made ed click for me.

And yes, I was disappointed that the author clearly didn't understand why ed has the UI it does. It's about the teletype, not the computational cost of having a WYSIWIG UI.

⬐ andrewksl

Yeah that video is all kinds of amazing. I also got lost down a several hour rabbit hole watching the guy and his buddies bring up an AGC and perform a simulated lunar landing with it. Thank you for sharing!

⬐ koolba

That video is amazing!

⬐ klysm

I desperately want to set up a teletype on my modern desktop - there’s just something so awesome about electromechanical interfaces with a lot more mechanical than electro.

⬐ NateEag

Agreed. I have some mechanically-minded young sons who I'm hoping to introduce to computing by way of a teletype of some sort.

⬐ throw0101a

Bonus points for splicing in ElectroBOOM full-bridge rectifier clips.

Saw this on YouTube last night;

https://www.youtube.com/watch?v=2XLZ4Z8LpEE

A facinating video that is part of a series going into the restoration of a 1930 Model 15 Teletype. In this video, they use it as a terminal for Linux.

⬐ lordleft

Amazing video. A lot of the quirks of UNIX and editors like vi make way more sense when you become aware of the role of the teletype in early computing.

⬐ JdeBP

It is a shame that there are no @ or #, otherwise xe could have demonstrated why the old defaults for the line discipline's special characters were as they were.

I notice that xe did not attempt to manually turn the iulcl or olcuc line discipline flags on with stty. Linux does not actually support xcase, though, not that there is a backslash anyway. (-:

⬐ dboreham

Editors like ed. Vi was waaayyy post teletype.

⬐ klysm

Still definitely has some influence though even if it was post teletype

⬐ ink_13

vi is so-named because it is based on VIsual mode for the standard EDitor. There's less distance than one might think.

⬐ JdeBP

That includes the distance between the X and D keys? (-: ex, not ed.

⬐ ink_13

ex is the EXtended standard editor, so it's in the path, sure. But vi and ed actually have many of the same commands.

⬐ JdeBP

You are still claiming that ed is the one with the visual mode?

⬐ jv22222

Finally, existence proof for all those Hollywood movies where the hero macgyvers a vacuum cleaner and a radio into a multi dimensional portal.

I mean, it proves you can upvert old stuff anyways ;)

⬐ hexadec

Hacker voice "I'm in" and the telex sounds off in the background.

It is interesting how you can track the history of remote terminals and make them work at all. It shows the true value of clear documentation.

⬐ Animats

Yes, it does. Those machines are very well documented. Here are the manuals:

http://aetherltd.com/manuals.html

⬐ derefr

Has anyone ever tried building one of these from scratch just from the manuals? That sounds like it'd be a fun joint EE + machining project.

⬐ Ericson2314

Ah.... back when we documented things.

⬐ rbanffy

Imagine not having to rewrite all the docs every six months...

⬐ vanderZwan

> Hacker voice "I'm in" and the telex sounds off in the background.

In the video it's the other way around: he logs in from the teletype around the ten minute mark. So I guess that kind of "proves" that a time-traveling dieselpunk hacker genius should be able to do the same ;)

⬐ donaldihunter

This reminds me of the Model 33 [1] we had connected up to a ZX Spectrum [2], back when I was a kid.

[1] https://en.wikipedia.org/wiki/Teletype_Model_33

[2] https://en.wikipedia.org/wiki/ZX_Interface_1

⬐ kbr2000

Cool! Made a "light" attempt at this when I was a kid, hooking up a matrix printer to my MSX computer [0], and learning BASIC's PEEK and POKE from my dad, to make a kind of typewriter: type a character, it prints at the curpos and advances the printhead; backspace moved the head one place back; return advances the page one line. Lots of fun :)

[0] https://en.wikipedia.org/wiki/MSX

⬐ IIAOPSW

So I currently have some Google cloud credits for a very computationally intense project. I have a 160 core VM with Debian on it and every time I start up the terminal it blows my mind that this blinking little cursor costs ~$17k per month (if I left it on). For the sake of achieving ludicrous anachronism, I now want to hook this machine up to the teletype.

⬐ lqet

Next step: Using a a Linotype [0] as a Linux terminal :)

I would love to have my terminal output cast in lead!

[0] https://en.wikipedia.org/wiki/Linotype_machine

⬐ rini17

Or as output for web engine. To drive home the phrase "Reflows are expensive".

⬐ herpderperator

This is super cool, but the fact that it only prints uppercase characters would be a nightmare if a standard case-sensitive filesystem is used.

⬐ fiddlerwoaroof

This is why you use HFS and a language like Common Lisp that is case insensitive.

⬐ kps

That's why `stty lcase` exists.

⬐ rbanffy

Model 33's also didn't have lowercase. It was not that common in terminals until the early 70's at least. The DEC VT05, for instance, didn't have lowercase.

⬐ dboreham

If we're playing competitive nostalgia, I owned (and used) a 5-channel teletype (electromechanical, lots of oil). Not having lower case would have been sheer luxury.

Interesting perspective when you realize you're looking at a UART implemented in tin.

⬐ rbanffy

If we are competing, you win.

I briefly used a 33 (as a peripheral to a CNC training computer) and I still miss that cadenced hum.

⬐ JdeBP

This would not have wholly worked with Linux. As I've noted elsewhere in this discussion, Linux does not support all of the Unix mechanisms. It does not implement the XCASE line discipline flag; so, unlike on Unix, on Linux one cannot use the xcase mechanism to get lowercase on an uppercase-only terminal.

FreeBSD doesn't support the Unix mechanism, either. Nor does NetBSD.

Xe could have connected it to an OpenBSD system. OpenBSD still supports the whole mechanism.

* https://github.com/openbsd/src/blob/57d747eef2b80ca9ffb95407...

⬐ ddevault

This is amazing! I'm very jealous. I've wanted to get ahold of these to do the very same thing for a long, long time. I made do with a cheap hack instead:

https://drewdevault.com/2019/10/30/Line-printer-shell-hack.h...

⬐ woodrowbarlow

jsyk, it looks like spacepub.space has an expired certificate, so your embedded video on that page isn't loading.

⬐ ddevault

Thanks, I noticed that too. I'm transcoding the longer video to rehost it myself.

⬐ type0

Great hands on Ed demonstration, not that you would need an actual tty for that but it puts things in perspective.

⬐ earthboundkid

In college, I wanted to buy a vterm for connecting to my laptop and being cool, but I couldn’t find one on eBay for college student prices.

⬐ phreeza

Fascinating to think that Unix is older than this teletype was at the inception of Unix...

⬐ harrygeez

This is glorious. I'd love to have one of this at home, just for the novelty

⬐ donaldihunter

Ideal for SMS. The Steampunk Message Service.

⬐ tpmx

How is the decoding logic implemented inside these machines?

Any informative websites?

⬐ lokedhs

He has this playlist on the same channel where they restore the Model 19, and they explain in detail how the decoder works:

https://www.youtube.com/watch?v=_NuvwndwYSY&list=PL-_93BVApb...

⬐ tpmx

Could you give us a brief summary? Is it purely mechanical? Any relays/tubes?

⬐ lokedhs

It's purely mechanical. I'm really not the right person to explain this, but the second video in the playlist explains it.

⬐ WhyNotHugo

This is beautiful.

⬐ knowaveragejoe

Wonderful youtube channel! I recommend it to anyone interested in retro hardware, in particular hardware reverse engineering.

⬐ non-entity

Awesome! These are the the type of projects I want to so, but am limited by my electronics ability.

⬐ kbr2000

Well, good luck! Remember it's never too late to learn something ;)

⬐ Animats

Model 15 machines have such a long life. I've restored two of those, plus three Model 14 machines, an earlier 1920s design. My machines have been to about a dozen steampunk conventions.[1] People send in their messages by texting, and they're printed on the Model 15, then delivered by a messenger. The video shows two acting students running our steampunk telegraph office. They're great at it. Web site: [2]

For smaller conventions, we have a semi-portable, a Model 14 tape printer in a road case made to fit. The tape is pasted down on telegram blanks, just like real telegrams up to the mid-1950s.

I normally run these off EeePC subnotebooks that run XUbuntu Linux. Those subnotebooks are about $30 on eBay, so I bought some of them for small projects. It's like having a Raspberry PI with a keyboard, screen, battery, and power supply all in a convenient clamshell case. I could run them as a Linux terminal, but I usually run them with a Python program that performs the telegraph office functions.

The lack of lower case is less of a problem in this application than the lack of emoji. I put the entire dictionary of emoji names into the program, and it spells out the emoji as (happy face), etc. That's amused some people who sent emoji-heavy messages.

The Right To Repair people would love those machines. Every part is individually replaceable. The price of this is a huge number of adjustments, plus annual oiling and cleaning. Few people today would put up with that much periodic maintenance in an office machine. It does let them be restored a century after they were built.

[1] https://vimeo.com/124065314

[2] http://www.aether.ltd

⬐ wpietri

I should also point out a friend's project, Teletweety, a Model 28: http://www.teletweety.com/

⬐ tomjen3

That video is amazing. My love of tech and history coming together.

⬐ Aloha

That's the thing about tech of that era, a moderately equipped machine shop can build almost any of it.

If there was a big crisis, We could retreat back to 1930 level of technology with relative ease in fact, maybe even later. That gives us radio, telephones, telegraphy, et al. All that tech can be made in small workshops.

⬐ derefr

That's, to me, the amazing thing about machining: pretty much any invention from the dawn of civilization up until the vacuum tube can be made in "a moderately equipped machine shop." Because, if a part requires a custom tool to build, it's very likely there's a version of that tool you can build with just the same 1930s tech you use to build anything else, in about four hours.

A good chunk of hobbyist-machinist YouTube is essentially just people bootstrapping themselves into a complete shop's worth of tools starting from three or four primitives, and it's kind of wonderful to watch.

(I'm always kind of disappointed whenever one of these hobbyist folks get a CNC mill or something, because it throws off that bootstrapping feeling. I know it was never their goal, but they were coincidentally pulling it off until that point.)

⬐ Aloha

Including the vacuum tube, you just need glassblowing equipment and a good vacuum pump, and some other specialized tools. That said, the first voice transmissions used either alternators or high speed rotary spark gap transmitters.

Another thing is audio amplification can be done without tubes or transistors, you can use a mechanical amplifier which is literally a transducer that is mechanically coupled to a carbon microphone, and a local power source (battery) making it possible to build analog phone lines that run several hundred miles without tube type amps.

See https://www.youtube.com/user/glasslinger

⬐ jdkee

Speaking of vacuum tubes, this gentleman makes them by hand.

https://www.youtube.com/watch?v=EzyXMEpq4qw

⬐ derefr

Sure, I mostly brought up vacuum tubes as an endpoint because constructing the specialized tools to make one is no longer a four-hour job. You run into a wall where, to get to the point where you can do the glassblowing, you have to first bootstrap an entirely-separate set of primitives (kiln, quench, anvil, grinding/polishing stones, etc.) that you may not have needed up until that point if you’d just been working with scrap stock.

(And then the same is true of everything after that, because transistors require photolithography, and photolithography requires good lenses.)

Of course, if you’re unlocking your tech-tree in a breadth-first direction, you’ll already have the glassworking primitives around due to them being common prerequisites for refining metal ore :)

⬐ treve

Do you have a link to one of those videos? Would love to see one. Also reminds me of Factorio

⬐ zipwitch

Anyone who is interested in this sort of thing may wish to take a look at the seven-book Build Your Own Metal Working Shop From Scrap series by the late David Gingery. While intended as a guide for the hobbyist, the series could easily serve as a blueprint for how to go from scraps of metal, wood and earth to a fully functioning machine shop in a post-apocalyptic scenario. And if you add in Herbert and Lou Hoover's excellent translation of De Re Metallica you're well on your way to having a blueprint for rebuilding humanity's pre-WWII tech base from scratch.

⬐ kbr2000

Thanks, first time I've heard of them, will be going through those (they seem to be available at archive.org [0]) soon!

I'd like to point out another interesting 18-part series of videos about prototyping (in his words "a short course on how to build stuff" :)), by engineer/inventor/professor Dan Gelbart: [1]

[0] https://archive.org/details/GingeryMetalWorkingShop/mode/2up

[1] https://www.youtube.com/watch?v=xMP_AfiNlX4

⬐ Animats

Er, no. Making a Teletype machine required a sizable plant. Morkrum had over 200 employees before they shipped their first production machine.

Those machines required a large number of precision stampings and small machined parts. Lots of custom tools and dies. Tooling up to make all those was a big job. Once they had all the tooling and plant, the Model 15 was cheap to make, despite its complexity. Teletype tried making a cheaper, simpler Model 26, but it cost more to make than the Model 15 because the manufacturing process for the heavy-duty machine was working so well.

From the beginning, most Teletypes were rented, not sold, and came with maintenance included. So the machines had to be reliable. The Model 15 seems way overdesigned. Flat parts were both hardened and Parkerized, a caustic process that deposits a rust-resistant oxide and turns metal grey. (Sometimes used for guns.) Fine-thread screws. Lock washers on every screw. Insulation that won't age or crack. Plus, the keyboard, typing unit, and motor are all very easily replaceable; they even disconnect electrically and slide out. The screws and round parts are all custom. They must have had a huge number of automatic screw machines turning them out. All round parts fit precisely.

This was not made in a small workshop. More like a factory that covered a city block in Chicago.

⬐ wil421

Why would you make a 1930s machine using 1930s processes? Use a CNC machine, metal injection molding, and change the design to be able to use off the shelf screws and bolts where ever possible. Forgot all the brass, looks nice but it will add to the build.

⬐ Aloha

That's all true, but it's only true if you're making thousands of them a year, not hundreds. Much of what was stamped could be machined instead, you use stamping for economy and labor savings.

WE Hawthorne Works in Chicago was similarly large, and to build in quantity you'd need it to be just as large now, but to build a couple hundred strowger switches a month? Not as large.

The hardest part of bootstrapping to 1930 is making copper wire - doubly so for wire suitable for electrical coils.

⬐ prashnts

Reminds me of this article on the complexities at different levels of abstraction (sorta). http://johnsalvatier.org/blog/2017/reality-has-a-surprising-...

⬐ rini17

You mean, like, using 2000's CNC to manufacture 1930's teletype parts?

⬐ Aloha

or manually operated mills too, the technology need not be advanced.