In 1979, healing just a few months before he died, John Mauchly had a letter published in DATAMATION.  Examples of his writing are rare, but here he clearly wanted to have his say.  In this short piece he describes how he and Pres Eckert, in the wee hours of 1944, worked out the stored-program architecture of EDVAC, the successor to ENIAC.  Later they told John von Neumann, who published it as his own work, and who never repented for it.

Mauchly also brings up the little-known fact that 25% of the ENIAC’s electronic storage was dedicated to programming.  Perhaps it deserves some consideration as a stored-program computer?  The letter also describes some features of BINAC, an under-appreciated innovation.  This was at the time that Burks and Goldstine were trying to drain as much credit away from Eckert and Mauchly and towards Atanasoff and von Neumann as they possible could.  It turned out to be Mauchly’s last published words.

Stored Programs by John W. Mauchly

This desktop ENIAC simulator lets you learn about the ENIAC the way any respectable hacker does – by monkeying with it.

Our favorite 30 ton computer is turning 65 and not looking great for its age.  But although the original is currently chopped into pieces and scattered across the world like Voldemort’s horcruxes, clinic there is a working ENIAC.  It is a java applet that you can download and play with here.

The desktop version of ENIAC is by Till Zoppke, view who says he was inspired by the ENIAC-on-a-chip that was built at Penn.    It is pretty impressive; you can move patchcords, set switches, and watch it go through it’s paces on a couple of sample programs.  Try to break it, it’s only fair.  There are some tutorials posted there too, for when you get stuck.

An article about the simulation, written by Raúl Rojas and Till Zoppke, is available there, called “The Virtual Life of ENIAC.” It is all hosted by our friends over at at Konrad Zuse Internet Archive.

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