The Speculist

Recently Phil and I have speculated that difference engine models - mechanical computers - might prove useful again at the molecular level.

It's perhaps useful also to remember why mechanical computers were abandoned. A 1989 interview of computer pioneer J. "Pres" Eckert was just published this month. Eckert, a co-creator of ENIAC (the first large-scale, electronic, digital, general purpose computer), spoke about the state of the art prior to ENIAC:

[A Vannevar Bush machine] could solve linear differential equations, but only linear equations. It had a long framework divided into sections with a couple dozen shafts buried through it. You could put different gears on the shafts using screwdrivers and hammers and it had "integrators," that gave [the] product of two shafts coming in on a third shaft coming out. By picking the right gear ratio you should get the right constants in the equation. We used published tables to pick the gear ratios to get whatever number you wanted. The limit on accuracy of this machine was the slippage of the mechanical wheels on the integrator.

It's been awhile since programmers used screwdrivers and hammers.

That made me say, "Let's built electronic integrators and stick them into this machine instead of those wheel things." We added several dozen motors and amplifiers and circuits using over 400 vacuum tubes, which, as electronic things go, is not trivial. The radio has only five or six tubes, and television sets have up to 30.... The Bush Analyzer was still essentially a mechanical device.

That led me to examine if I could find some way to multiply pulse numbers together so I didn't need gears -- then I could do the whole thing electrically. There's a theorem in calculus where you can use two integrators to do a multiplication. I talked with John Mauchley about it. Just who put in which part is hard to tell, but the idea of doing the integrations by counters was mine.

The ENIAC was the first electronic digital computer and could add those two 10-digit numbers in 0.0002 seconds -- that's 50,000 times faster than a human, 20,000 times faster than a calculator and 1,500 times faster than the Mark 1. For specialized scientific calculations it was even faster.

So it's a myth that ENIAC could only add, subtract, multiply and divide.

No, that's a calculator. ENIAC could do three-dimensional, second-order differential equations. We were calculating trajectory tables for the war effort. In those days. The trajectory tables were calculated by hundreds of people operating desk calculators -- people who were called computers. So the machine that does that work was called a computer.

So what did they give you? Did they say, "Here's a room, here are some tools, here are some guys -- go make it?"

Uh-huh. Pretty much

...

Was it you or was it the times?

Well, I may have been uniquely prepared. I was very good in math and I was fascinated with all electronics. I was designing electronic gadgets as a kid and I not only did academic math, I studied business math. Maybe I had the right fusion of interests. But every inventor stands on the pedestals built by other people. If I hadn't done it, someone else would have. All that any inventor does is accelerate the process. The main thing was we made a machine that didn't fail the first time. If it had failed, we might have discouraged this line of work for a long time.

This interview is being published to celebrate the 60th anniversary of the ENIAC (...only twice the age of the Apple 1).

Read the whole thing.