Retrotechtacular: Where The Linux/UNIX TTY Came From


From time to time we realize that sayings which make sense to us probably will have no meaning for future generations. Two of the examples that spring to mind are “hang up the phone” or in a vehicle you might “roll down the window”. And so is the case for today’s Retrotechtacular. Linux users surely know about TTY, but if you look up the term you actually get references to “Teletypewriter”. What’s that all about?

[Linus Akesson] wrote a fantastic essay on the subject called The TTY Demystified. We often feature old video as the subject of this column, but we think you’ll agree that [Linus’] article is worth its weight in film (if that can be possible). The TTY system in Linux is a throwback to when computers first because interactive in real-time. They were connected to the typewriter-mutant of the day known as a teletype machine and basically shot off your keystrokes over a wire to the computer the terminal was controlling.

This copper pipeline to the processor is still basically how the terminal emulators function today. They just don’t require any more hardware than a monitor and keyboard. We consider ourselves fairly advanced Linux users, but the noob and expert alike will find nuggets and tidbits which are sure to switch on the lightbulb in your mind.

[Thanks Chuck]

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.

27 thoughts on “Retrotechtacular: Where The Linux/UNIX TTY Came From

  1. ‘Two of the examples that spring to mind are “hang up the phone” or in a vehicle you might “roll down the window”’

    Hmm, I do both of those things. No teletype machine though alas.

      1. So you can give them a slap and tell them not to be facetious?

        I’m 25 this april. While I accept this means I’m no longer “kids of today” I refuse to believe that the world has changed that much. The type of phone on my wall is still on the market and they’re still manufacturing cars with manual windows.

        If the example had been “dial a number” then I would have to agree though my niece does like to play with my old rotary phone so at least one child knows what they are :)

        1. Better yet, what else would you call those actions?

          There isn’t a word for entering a phone number into a telephone and calling it except “dial”. On the contrary, the dictionary definition of the word “dial” is now:

          : to select (a series of numbers) on a telephone by turning a dial or pushing buttons

          The word “dial” hasn’t actually ever meant specifically a round instrument that you turn. That’s why they were called rotary dials to start with.

          1. Yes and no lol,

            An example would be computer components. For example DDR RAM was called DDR RAM until we had DDR2 RAM at which time DDR RAM was unofficially called DDR1 RAM.

            In telephony the word dial came from an ancient object called a sun-dial which was the earliest of clocks. Some other examples are the old clock face, the old round speedometers in cars etc. All were round. However the word dial meant they had graduated units.

            Similarly a phone dial was just called a dial until we has press-button dialling at which time the older dial was called a rotary dial.

            So technically you are correct as the original meaning of dial was ‘graduated units’ however the historical use of language has not followed the technically correct path.

        2. And Deloreans still being manufactured in Mexico, and companies still make reproduction Ford Model T bodies. Just because they’re still being made, doesnt mean the world hasnt moved on.

        3. I have three kids, ages 21, 19, and 10. They all have experienced the joys of a rotary, corded telephone. It’s the only one my wife and I allowed them to use because the cordless kept disappearing or was being used a inappropriate times

          We presented them with the option of using the rotary, tethered to the wall adjacent to the kitchen table. Yes we were able to hear what they said, we’re parents after all. The arrangement allowed us to correct any unwanted behavior while on the phone. Eventually having corded phones was so much better from a behavior management standpoint that we got rid of the cordless.

          I now have children that possess proper phone etiquette. Habits that have followed them on to their mobile phones. All except the 10 year old, that is. She is still “paying her dues”.

  2. I loved the old ttys. When you ran your program, the noise a tty made sounded very dramatic, like something important was happening. That’s one reason they’re shown in footage in old movies where the Big Story arrives in the newsroom. What wasn’t so fun was dealing with all the damned paper. Ditto for punch cards. If you had a big program, you carried it in a big tray like a long, low file drawer, and you had to have strong arms or a cart. Then there was the punched tape with the rewinding and repairing tears, and the slowness of punching it and reading it, and cleaning up the chad. Now that I think of it, the old days sucked.

  3. This sounds like something from history. *.nix is mentioned but what about windows?

    The other side of tty is console (con). When you open a dos box in windows then you connecting con to tty. Con is the keyboard and screen and tty is the dos interface.
    When you execute a batch file (.bat) then you are connecting the file (stream) to tty.

    To put it simply con is the connection viewed from the process end (ie dos) and tty is the connection viewed from the user end (terminal).

    In the language ‘c’ console (the other end of tty) is in stdio.c or stdio.cpp

    So this all still exists! I am typing into my browser with the OS acting as con and the browser acting as tty lol.

    1. Actually the DOS CON: and TTY: devices predate the IBM PC. They were grandfathered in from the CP//M IOByte io redirect variable. IOByte defined 4 virtual devices: LST (standard hard copy device), PUN (standard paper tape punch) , RDR (Paper tape reader ) and CON (console terminal . Each of these devices could be mapped to 1 of 4
      hardware io devices. The mapping were determined by bit pais in a single byte.
      In the CP/M world, there was considerable variety in design. Many computers use a serial terminal for the console, others had a built in memory mapped CRT . Some CP/M computers such as the HP 125 upgraded upgraded a standard terminal with a logic board containing an 8 bit computer and a fully functional terminal.
      I started out with a Panasonic JD850M, which sported a built-in CRT and 3 serial ports. My printer was an old ASR43 teletype at 600 bps, and I had a 300 bps acoustic coupled modem on the second port., and later configured the third port to communicate through a null modem connection using RCP/M. For my terminal program, I wrote a terminal program in 8085 assembly that emulated an old LSI ADM3 termina, with xmodem thrown in for good measure. I simply remapped the rdr and pun devices to serial port 2 for the modem connection. left the console at its default

  4. I have an IBM 3151 dumb terminal here at home. It was hooked up to an old Dell notebook for some time running Debian 2.2 potato. Probably I’ll load up hackaday retro on it just for fun.

  5. In the event this bit of trivia* is or somehow could be important knowledge for the future, perhaps a Wikipedia entry should be created? So anyone searching for TTY will see the current disambiguation page for TTY. Chances are Wikipedia will be more enduring that personal efforts maintained on the web,when they are subject to the creator finance’s and life span.

    *Respectfully way terminology or slang become common place is trivia. The only reason I can thing of why roll up a car window become the slang and not crank up the window, is that side curtains preceded door glass and they where rolled up when not needed. Think about it; a crank (manual or power) still lifts/lowers motor vehicle door glass, and glass is impossible to roll up.

  6. I have a 17 year old cousin. Her father needed to borrow my truck one day, as his car broke down, and he needed to pick her up from school. (Her car was in the shop too, brilliant.) She got in, and couldn’t figure out how to put the window down. Manual, of course.

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