Building a 5-Ton Calculator From 19th-Century Plans

alphadogg writes "Starting in May, many will have the opportunity to see computing done the old-fashioned way: with lots of gears, a big crank, and some muscle. The Computer History Museum in Mountain View, CA, will unveil a new construction, the first in the US, of the 19th-century British mathematician Charles Babbage's Difference Engine No. 2, an improved version of his earlier design for a mechanical digital calculator. It weighs in at two tons more than the Difference Engine built in 1991 at London's Science Museum. Microsoft millionaire Nathan Myhrvold commissioned and paid for the US model."

Comments

Re:It's cool

[Adambomb]

yes, and we can all imagine a beowolf cluster of them, comparisons with automobile tonnage, and how in soviet russia, 2 tonn calculator uses YOU.

yep.

Re:150 years makes quite a difference

[gardyloo]

I don't know, but you can bet there will be "bad car analogies" analogies, mentions of some hot chick and grits, and complains about moderators.

Re:It's cool

[evanbd]

First, this is the Difference Engine No. 2, not the Analytical Engine. It's not Turing complete.

Second, the usual restriction on running something like Linux is lack of memory, not lack of a Turing-complete instruction set. Or, looked at another way, no one has ever or will ever build a Turing-complete machine, because they'll run into difficulty with the infinite tape.

Negative. This is a DFSM

[Theatetus]

It is possible using these materials and a potentially limitless but deterministic input source to make a universal Turing machine, but this device as designed and as it is not fully programmable (it was Ada Lovelace who pointed that fact out, along with a very early formation of the Church-Turing thesis when she commented in the margin that a suitably-designed engine could be alternately arithmetical or analytical depending on how the inputs and outputs were interpreted).

Re:Meh....

[Jeremy Erwin]

From Carol's site:

Babbage's design could evaluate 7th order polynomials to 31 digits of accuracy. I set out to build a working Difference Engine using standard LEGO parts which could compute 2nd or 3rd order polynomials to 3 or 4 digits You can compute 3rd order polynomials by hand without too much strain. Seventh order polynomials are too difficult to reliably compute by hand--the mind numbing tedium might get to you after a bit.

Nor can you build a seventh order difference machine out of legos.

Plastic gearing and axles are subject to large amounts of flex and gear lash, which can be a significant problem where any level of precision is required. Babbage's machine weighs five tons because it was designed to be precise. The museum's machine weighs five tons because it is intended to be a replica of what Babbage created, not just an amusing simplification.

You also forgot ...

[MindKata]

You also forgot the "I for one welcome etc.." quote. But then again, in this case, its brain would be so slow, we would all have died of old age, long before it would finally be able to think up its first great chess move, in how to take control of the Earth.

Still, it would be EMP proof, so although its slow, its hard to stop with impressive high tech scifi looking energy weapons ... well apart from it stopping due to rust or a spanner in the works etc..