IBM 1401

IBM 1401 video series playlist:

See my videos featuring the IBM 1401 at the Computer History Museum in Mountain View, California, USA

The IBM 1401, introduced in 1959 (see this period marketing video here), was the first truly widespread computer mainframe, with an estimated half of the world computers being IBM 1401 by the mid 1960's. A relatively small and affordable computer by IBM mainframe standards of the time, it is enormous and was very expensive by today's standards. It democratized the use of computers, which were previously only available to the largest companies, to mid-size businesses. Although the CPU was small and comparatively tame, and memory topped out at 16kw, its peripherals were top notch, some much better than that of the bigger scientific mainframes. The IBM 1403 printer, at 600 line/minute printer is still impressive today, and so is the IBM 1402 800 cards/minute punched card reader. Its ability to drive up to 7 of the magnificent IBM 729 7-track magnetic tapes sealed its market appeal for businesses with large databases, which were finally able to abandon their piles of punched cards.

Guy Fedorkow has written a most excellent introduction article for the museum.

Robert Garner has written a historical paper for the IEEE journal: "The legendary IBM 1401 data processing system"

If you want to know how it works inside, IBM 1401, A Modern Theory of Operation by Guy Fedorkow is a superb reference

Ed Thelen sprawling site will give you more info than you ever wished.

ROPE: the IBM 1401 Emulator and Development IDE

Now everyone can run his own IBM 1401 and write programs for it (using the Autocoder compiler) thanks to the ROPE emulator. In works on Windows, Mac and Linux. There is a giant quirk that the File->Open... menu does not work, but instead if you click on the Open... button on the editor window it will work. Don't ask...

(The source code for the ROPE project is here:

A library of example programs that you can run with it can be found here

To best learn how to program the very unusual IBM 1401, Ken Shirriff suggests the following:

A more exhaustive reference is available at:

The IBM 1401 runs Edith

The source code of Edith can be found here:

You can try it for yourself on the ROPE emulator.