1843: The Analytical Engine

In 1822, Charles Babbage, a British inventor and engineer, started working on the design of his Difference Engine, an automatic calculation machine that included printing of the resulting tables, in order to eliminate as many sources of human error as possible. 12 years later, he extended this concept to the more general Analytical Engine. This device was in fact the world’s first design of what we would now call a modern, general-purpose, fully programmable digital computer. The only problem with it? It arrived around 100 years too early. Various problems, related to the financing and manufacturing of the project among other things, prevented Babbage’s vision from being realised. Like his ideas, the understanding of how far-reaching and important they were went into a century-long slumber.

How closely does it resemble the architecture of a modern computer? The purely mechanical and steam-powered device (no electrical parts involved) would have included modules for data input and output, a memory unit, as well as an algorithmic processing unit. Programs, data to work on, and store/load instructions would have been fed to the machine on punched cards through three separate readers. Card reading motion was reversible, and the machine supported libraries of subroutines. Apart from a printer, output could be sent to a curve plotter or a card puncher, as well as triggering a signalling bell.

While the algorithmic unit, called the mill, would have operated on registers storing 40-digit numbers, the memory, also called the store, would have provided storage space for 1’000 50-digit numbers, which is equivalent to about 20.7 kB. Apart from basic arithmetic operations, the Assembly-like microcode language for the mill supported loops, as well as conditional jumps based on the outcome of number comparisons, which would in fact have made Babbage’s engine Turing-complete.

While the general public at the time was not able to comprehend Babbage’s ideas, his scientist contemporaries mostly thought that he was a dreamer who had lost touch with the realm of the possible. One notable and famous exception was Augusta Ada Byron King, Countess of Lovelace, a young mathematician who said of herself to be “fascinated by the universality of his ideas.” Italian Federico Luigi, Conte Menabrea, wrote a report about Babbage presenting the concept of his machine in 1842. Augusta Ada King subsequently started translating his report from French to English. As King had already been a personal friend to Charles Babbage for many years, and followed the development of the Analytical Engine for the past 10 years, Babbage asked of her to add her own thoughts as notes to the translation—the notes ended up being three times as long as the original report.

These notes, which have long since become computer science history, show how deep King’s understanding of Babbage’s ideas actually went. Apart from explaining some of the mathematical background left out of the report for conciseness, her more interesting contribution were thoughts about the operation and application of such a machine, should it ever be realised. She realised that while previous, single-purpose calculation machines required more manual interaction of the user, an automatic general-purpose computer in turn posed an increased responsibility on its programmer to put care into the design of his input. Computer scientists today know this dilemma as computers allowing us to “make the same mistake many times, really fast.”

And even more astonishing is the fact that Augusta Ada King was probably the first person to consider such a device to not only be used for science and calculations, but also art and entertainment. While even Charles Babbage himself seemingly did not see his machine as being of use to anyone but mathematicians, King noted that the machine does not operate on numbers per se, but symbols, and that if any other kind of data were to be translated into symbols to which the machine’s operations were applicable, the machine could work on it as well. She adds that if, for example, the “fundamental relations of pitched sounds in the science of harmony and of musical composition were susceptible of such expression and adaptations, the engine might compose elaborate and scientific pieces of music of any degree of complexity or extent.” This extension of Babbage’s ideas to the arts and, in fact, general data and information processing, seems almost prophetic from today’s point of view.

A point of debate is whether the program included in her notes, an algorithm to compute the Bernoulli numbers using the Analytical Engine, was actually written or only debugged by her. Belief that the former was true has earned Augusta Ada King recognition as the first real computer programmer, and has led to the U.S. Department of Defense naming a programming language in her honour—ADA. In an autobiographic work however, Babbage states that he wrote the program and King merely pointed out a mistake that he had made, before adding it to her notes. On the other hand, Babbage is said to have been very miserly in giving credit to others. Whatever the case may be, the fact remains that Augusta Ada King was an exceptionally intelligent and insightful mind, an unknowing and largely unheeded herald of the computer age.

And so was Charles Babbage himself. Researching his original plans, historians and engineers came to the conclusion that Babbage would probably have been able to fully realise his Analytical Engine even with the manufacturing processes of his time, had he been able to overcome his problems in financing the project. Charles Babbage never gave up on the idea that one day, his vision would be realised: “As soon as an Analytical Engine exists, it will necessarily guide the future course of the science.”

« Back to Part I — Prehistory

References

• The History of Computing Project Timeline: 1830-1844
• Wikipedia: Analytical engine
• Wikipedia: Federico Luigi, Conte Menabrea
• Wikipedia: Ada Lovelace
• The History of Computing Project: Ada Byron King
• L.F. Menabrea – Sketch of the Analytical Engine Invented by Charles Babbage, with Notes Upon the Memoir by the Translator Ada Augusta, Countess of Lovelace
• Picture “Charles Babbage, obituary portrait”: Wikimedia Commons (Public Domain)
• Picture “Ada Augusta Byron King” by Margaret Carpenter: Wikimedia Commons (Public Domain)

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