The story of Mauchly and Eckert computers beyond ENIAC is murkier, stranger, and rather more interesting than the textbooks tend to let on. John Mauchly and J. Presper Eckert, the pair behind the famous ENIAC at the University of Pennsylvania, did not simply pocket their reputations and disappear after that machine made its mark. Holly Mengel of Penn’s Kislak Center for Special Collections, Rare Books, and Manuscripts has been drawing attention to the other machines the two went on to build, and the list is worth sitting with.
EDVAC, UNIVAC, and the machines most people have heard of
EDVAC and UNIVAC are the names that crop up whenever anyone reads a little deeper into computing history past ENIAC. UNIVAC, in particular, enjoyed a reasonable commercial run and even has a Disney connection, though the report of that story is one Mengel leaves for another time. EDVAC, meanwhile, was highly influential in shaping how stored-programme computers were designed in the years that followed. Neither machine is exactly obscure to anyone who has spent time with computing history, and both represent a logical continuation of what Mauchly and Eckert had started.
But the more telling entries on their post-ENIAC list are the ones that barely made it into the record at all.
BINAC, Skeduflo, and the Mauchly and Eckert computers that history mislaid
BINAC has a reasonable claim to being the first commercially produced digital computer, which would make it genuinely historic. The claim comes with caveats, however. The machine was reportedly fairly limited in what it could do, and, critically, it apparently never functioned correctly after delivery. According to the account Mengel surfaces, the customer disassembled the machine, shipped it to a secure facility, and brought in a newly graduated engineer to rebuild it. That effort did not go well. Whether BINAC truly earns the “first commercialised digital computer” title is, accordingly, a point one can argue either way.
Then there is Skeduflo, which is the sort of machine that makes you want to find one in a skip. It was a 75-pound analogue computer built for critical path method (CPM) analysis, and it arrived at its answers in a satisfyingly hands-on fashion. The operator set up the problem using a patchboard and potentiometers, and the result emerged on an analogue plotter. No screen, no keyboard, no operating system to negotiate: just carefully set resistances and a pen tracing the output onto paper. The details of Skeduflo come from a Project Management Institute interview with Morgan Walker and Jim Kelley, which appears to be about the only detailed record of the machine that survives in accessible form.
The name alone is worth a moment. “Skeduflo” has the ring of a portmanteau built from “schedule” and “flow,” which would fit the CPM application neatly, though the report does not confirm the etymology. What it does confirm is that the machine lived in a rather large suitcase, which puts it in that fascinating mid-century category of portable computing that meant something very different from what the word implies today.
There is a broader point here about what prolific inventors actually do with their time. Mauchly and Eckert did not finish ENIAC and retire. They kept building, kept experimenting, and produced machines that ranged from the historically contested (BINAC) to the practically obscure (Skeduflo). The Penn Libraries holdings that Mengel draws on suggest there is still archival material on these machines waiting for the right researchers to dig into it properly. For anyone with an interest in the years when computing was still being invented in real time, that is a genuinely open seam.
