Siamese twin typewriters

by | Oct 3, 2018 | Uncategorized | 8 comments

In my recent series on little-known typewriters I included this photo of a double IBM unit.

Such machines were used when one set of characters was not enough. Maybe the typist needed two different alphabets, or needed to insert a wide variety of symbols in a text. Pulling the paper out and inserting it in a separate typewriter was not a good option, because the text would almost surely be misaligned. The solution was this Siamese twin arrangement.

IBM was not the only company to create such devices. Frans van de Rivière just alerted me to this dual Optima which is currently for sale in Germany.

The British company Imperial also offered “dual-unit typewriters.”

Olivetti offered them too.

Of course, such devices were made obsolete by the Selectric and later daisywheel typewriters, which allowed you to swap the type element.

In fact, as typewriter collectors know, many early typewriters had interchangeable type elements, too. For example, the elusive Blickensderfer Electric. (This one was sold by Auction Team Breker in 2007.)

Another good solution to printing individual special symbols was Smith-Corona’s Changeable Type system.

Want to type an emoticon? Smith-Corona’s got you covered:

Brother offered a comparable system, Dial-A-Type (image source: Davis Typewriter Works).

Finally, I’ll mention the Typit system, invented by Robert Twyford. More information in Klaus Brandt’s story on p. 12 of ETCetera no. 99.


  1. Ted

    Excellent overview, and ya should mention Hammond/Varityper (:

  2. Richard P

    True — that was one of the most enduring typewriter designs in history (about 1890-1970), and it provided interchangeable type shuttles from the start. And here's a shout-out to many other early machines with interchangeable elements: Postal, Moya, Crandall, Lambert, Munson/Chicago, Sterling, Keystone, and the rest.

  3. Bill M

    The Siamese twins of typewriters. i never knew such devices existed. I do have some Change-A-Type though.

  4. phxxer

    The dial-a-type reminded me of a type bar I saved from an old Burroughs accounting machine. It had 4 elements: month,2 # wheels, and a year wheel. The operator using this key, could type the date in one stroke, just set it to the correct date first thing in the morning. Phil

  5. Brian Josephson

    Our theory group had one of these typewriters to allow Greek characters to be typed into equations. It was similar to the Imperial one shown here (3rd one down) in that it had green buttons to press on each side, which caused the platen to be raised, moved across to the other keyboard, and then lowered again (presumably it was plugged into the mains to provide power for this operation). An impressive machine!

  6. Richard P

    Thanks for your report!

  7. Cookee_NZ

    Otherwise known as a "Tandem Typewriter" – that's how IBM referred to theirs


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