Where is the difference engine

With the construction project stalled, and freed from the nuts and bolts of detailed construction, Babbage conceived, in , a more ambitious machine, later called Analytical Engine, a general-purpose programmable computing engine. The Analytical Engine has many essential features found in the modern digital computer.

It was programmable using punched cards, an idea borrowed from the Jacquard loom used for weaving complex patterns in textiles.

The Engine had a 'Store' where numbers and intermediate results could be held, and a separate 'Mill' where the arithmetic processing was performed. It had an internal repertoire of the four arithmetical functions and could perform direct multiplication and division. It was also capable of functions for which we have modern names: conditional branching, looping iteration , microprogramming, parallel processing, iteration, latching, polling, and pulse-shaping, amongst others, though Babbage nowhere used these terms.

It had a variety of outputs including hardcopy printout, punched cards, graph plotting and the automatic production of stereotypes - trays of soft material into which results were impressed that could be used as molds for making printing plates. The logical structure of the Analytical Engine was essentially the same as that which has dominated computer design in the electronic era - the separation of the memory the 'Store' from the central processor the 'Mill' , serial operation using a 'fetch-execute cycle', and facilities for inputting and outputting data and instructions.

Calling Babbage 'the first computer pioneer' is not a casual tribute. With the groundbreaking work on the Analytical Engine largely complete by , Babbage began to consider a new difference engine.

Between and he completed the design of Difference Engine No. This Engine calculates with numbers thirty-one digits long and can tabulate any polynomial up to the seventh order. The design was elegantly simple and required only approximately a third of the parts called for in Difference Engine No. There were enough 'registers' for seven differences, allowing it to compute digit values for polynomials with terms up to x 7.

The Engines. How it Works. Key People. The Difference Engine is a calculator. It prepares numerical tables using a mathematical technique known as the method of difference. Today such tables — the kind often used in navigation and astronomy — would be computed and stored electronically. Nearly a century and a half ago, the Difference Engine did much the same work, but slowly and mechanically.

Each of its long shafts holds disks, and each disk has wheels with ten teeth that correspond to marks in the disks. A scientist could set the disks with known figures, odd or even, turn a crank, and by reading down on each shaft, find the result of a calculation. This particular "engine" could also print out its answers. Sold to an observatory in Albany, New York, it was given to the Smithsonian in The Scheutzes had no interest in pleasing design.

Their device worked well, though, for they had followed to practical completion the concepts of one of the 19th century's most brilliant minds. Inventor and philosopher, Babbage produced a prototype of the original Difference Engine as early as , then kept adding refinements without ever quite finishing it. He enthusiastically endorsed the work of his friends Georg and Edvard Scheutz.

But during the years it took them to complete their machine, the inventor's mind was groping toward a mechanical device that would go far beyond calculation. It would actually store the data that it produced, then reuse the information to add more. Babbage described this process as "the engine eating its own tail. What he foresaw was a primitive computer. As his biographer, Anthony Hyman, wrote, "Babbage worked by himself, far ahead of contemporary thought. He had not only to elaborate the designs but to develop the concepts, the engineering, and even the tools to make the parts.

In fact it was not one engine, but a class of computers. He built parts of his analytical engines just as he built parts of his difference engines. Ada Byron's notes fixed the Analytical Engine in our minds as a single machine.

She left us with a keen sense of unfinished business. But by focusing our vision of Babbage, she also limited it. Now we begin to see that he was even more advanced than we realized. With a little more government funding, he might've changed the course of history. I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work. Thank you to Ryan Wickland for his link documenting Ada's work. Associated Press, Calculator built from design works perfectly, scientists say.

The Houston Post.