Queen Victoria’s Secret (Teletype And COSMAC Elf)

We don’t really think anyone in the Victorian era had a COSMAC Elf — the homebrew computer based around the RCA 1802 CPU. But if they did, it might have looked like [Daniel Ross’] steampunk recreation of the system that includes an appropriate-looking teletype device. You can see the thing in a series of videos, below. There are actually quite a few videos showing different parts of the system, along with several blog postings stretching back a few months.

A magic eye tube doesn’t look out of place in this build. We especially liked the glass tube displays and the speaker, although we thought the USS Enterprise looked out of place with the technology based on stone knives and bearskins, to paraphrase Mr. Spock. On the plus side, the VFD displays have the right glowing look, although a Nixie would have been pretty good there, too.

The videos don’t have much detail, but the blog posts do if you wanted to attempt something similar. Honestly, 1802 system design is pretty easy thanks to the its on-chip DMA that allows you to load memory from switches with no actual software like a monitor. The teletype started out life as a Remington #7 from around 1900, although another newer machine donated parts to get everything working. It is a testament to how well things were built then that it took as much abuse as it did and still has working parts.

We have a soft spot for the 1802 — it was a very good design for its time. We’ve even gone as far as to simulate it.

15 thoughts on “Queen Victoria’s Secret (Teletype And COSMAC Elf)

  1. LOLO the Cosmac elf ( RCA 1802) the fist microprocessor I ever encountered, One of th3e electronics mags had a build project and a friend of mine got a development kit when we were both in the Navy. mid 70’s programed with toggle switches and data and addresses vied via a plethora of LED’s.. I later had to program many phone systems that way… good times

    1. Heh, my first “computer” was an RCA COSMAC VIP – aka an ELF with this neat blocky video output, and a keypad. About as different from this steampunk recreation as possible.

  2. IIRC a Magic Eye is a circular display looking end-on at a tube. The wedge of denseness angle varies with the control signal. They were often used with one half blocked from sight to get a half-Moon look. I think the one in this project is the horizontal bar type display where you are viewing inside trough the curved side of the tube.

    The are great fun in a dim “radio shack” tuning in a faint signal.

    1. This project is a wonder and is way beyond the “gluing gears” stage.
      Steampunk ≠ historical re-enactment. It is powered by whimsy not chronological pedantry.
      It’s meta-temporal, it’s hyper-vintage, it’s retro-futuristic ” and ah, no that’s it. It’s the vibe. I rest my case.”


    1. I am in a tourist area and there is a shop that does that. Their big thing is to screw some pipe sections together, wire in s LED Edison light bulb and call it a “Steampunk” lamp. Tourists actually buy this crap.

  3. I didn’t think much of the 1802 until 45 years later, because the instruction set and way of thinking was so alien to Intel/Motorola. It had some features that were very cost effective for a small low chip count system and the power specs were amazing in its time.

    I spent a lot of money in the 70’s on microcomputers and never got anything running to the point that a VIP Kit could have gotten me to for a lot less.

  4. Some of those COSMAC processors were radiation-hardened for space flight. With waves of cascading nuclear explosions lighting up the horizon, that that might be able to type out humanity’s epitaph.

    Trivia: AFAIK, the COSMAC can clock down to almost nothing, like single digit Hertz.

  5. This build is extravagantly detailed, kudos! It reminds me of a steampunk project that remains trapped in my imagination: to take Sydney Padua’s rendering of the Analytical Engine, and imagine the look of the device after several generations of mechanical optimization using pocket watch parts.

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