Diatype, introduced in 1960, was the first phototypesetting system from the well-established type foundry H. Berthold AG. It was designed for typesetting layouts, ads, brochures and similar publications. It did not produce justified text and was not meant for newspaper or book publishing. Typefaces were held by a glass disc with characters stored as photo negatives. An experienced operator could set around 2000 characters per hour. Swapping the disc to access a different font took roughly 30 seconds (Schmitt 1976, 77).

The Diatype had no keyboard: type was set by selecting characters one at a time with a lever on the front of the machine and pressing a button on the lever handle. Moreover, the result was not visible until after the page was complete. The typographer laid out and measured the text ahead of time, then made use of mechanical indicators to determine the current location on the page. Mistakes were easy to make and difficult to correct and might mean resetting the entire page. As recalled by Alexander Nagel, an experienced typographer:

In Berthold's instructions it said you should sit in a room that is extremely quiet and that describes it exactly, you shouldn't let yourself be distracted in the process because otherwise you could definitely become befuddled (Deutsches Technikmuseum 2022, 14:19).

On the other hand, the Diatype gave graphic designers almost limitless flexibility. Character, word and line spacing were under the control of the operator in a way that was impossible for Linotype and other line-casting machines.

The original characters from which the disc was created were large positives on transparent, letter-size plastic sheets. The huge reduction in size when projected onto the disc meant that the resulting characters were precise and high quality (Deutsches Technikmuseum 2022, 20:16).