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1843 __ « The Sketch of the Analytical Engine »
Ada Byron, Lady Lovelace (1815-1852)
Comment : Ada Byron, Lady Lovelace, met Charles Babbage at Cambridge. Babbage had partially built a calculating machine, or 'Difference Engine', and was planning a more sophisticated 'Analytical Engine'. This was an early model for a programmable computer, and Ada Byron immediately recognised the potential for the 'universality' of the device. Writing in "The Sketch of the Analytical Engine" of 1843, she describes all aspects of Babbage's machine, including this passage about its musical applications. (Andrew Hugill)The analytical engine, an important step in the history of computers, was the design of a mechanical general-purpose computer by English mathematician Charles Babbage. In its logical design the machine was essentially modern, anticipating the first completed general-purpose computers by about 100 years. It was first described in 1837. Babbage continued to refine the design until his death in 1871. Because of the complexity of the machine, the lack of project management science, the expense of its construction, and the difficulty of assessing its value by Parliament relative to other projects being lobbied for, the engine was never built. Some have said that the technological limitations of the time were a further obstacle to the construction of the machine, but this has been refuted by the "partial" construction of one of Babbage's machines by his son Henry, and now by the construction of one of his simpler designs by the British Science Museum. Indications are today that the machine could have been built successfully with the technology of the era if funding and political support had been stronger. Babbage's first attempt at a mechanical computing device was the difference engine, a special-purpose calculator designed to tabulate logarithms and trigonometric functions by evaluating finite differences to create approximating polynomials. During this project he realized that a much more general design was possible and started work designing the analytical engine. The input (programs and data) was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. It employed ordinary base-10 fixed-point arithmetic. There was to be a store (that is, a memory) capable of holding 1,000 numbers of 50 decimal digits each (ca. 20.7kB). An arithmetical unit (the "mill") would be able to perform all four arithmetic operations, plus comparisons and optionally square roots. Initially it was conceived as a difference engine curved back upon itself, in a generally circular layout, with the long store exiting off to one side. (Later drawings depict a regularized grid layout.) Like the central processing unit (CPU) in a modern computer, the mill would rely upon its own internal procedures, to be stored in the form of pegs inserted into rotating drums called "barrels", to carry out some of the more complex instructions the user's program might specify. (See microcode for the modern equivalent.) The programming language to be employed by users was akin to modern day assembly languages. Loops and conditional branching were possible, and so the language as conceived would have been Turing-complete long before Alan Turing's concept. Three different types of punch cards were used: one for arithmetical operations, one for numerical constants, and one for load and store operations, transferring numbers from the store to the arithmetical unit or back. There were three separate readers for the three types of cards. In 1842, the Italian mathematician Luigi Menabrea, whom Babbage had met while travelling in Italy, wrote a description of the engine in French. In 1843, the description was translated into English and extensively annotated by Ada Byron, Countess of Lovelace, who had become interested in the engine ten years earlier. In recognition of her additions to Menabrea's paper, which included a way to calculate Bernoulli numbers using the machine, she has been described as the first computer programmer. The modern computer programming language Ada is named in her honour. (Compiled from various sources)
French comment : La machine analytique ("analytical engine" en anglais) est une machine de calcul inventée et créée en 1834 par le mathématicien anglais Charles Babbage. Cette machine, commandée par le gouvernement britannique pour établir des tables de calcul sans erreur, ne fut jamais achevée. Malgré des différences notables de fonctionnement (elle fonctionnait à la vapeur avec des roues et engrenages mécaniques) elle est considérée comme l'ancêtre des ordinateurs modernes. La machine analytique devait fonctionner ainsi : 1) Un moulin devait faire les calculs, soit l'équivalent du processeur de l'ordinateur actuel. 2) Un magasin devait stocker les chiffres, soit l'équivalent de la mémoire informatique de l'ordinateur. 3) Les résultats pouvaient être imprimés. 4) La machine était commandée par des instructions sur des cartes perforées, issues des techniques du métier à tisser. C'était l'équivalent des programmes informatiques ou logiciels. La célèbre Ada Lovelace (fille de Lord Byron) a participé (à un degré qui fait débat) à leur écriture, faisant d'elle la première femme en informatique. On estime aujourd'hui que la machine complète aurait constitué un enchevêtrement de roues et d'engrenages mus par la vapeur et prenant la place d'une locomotive. La machine analytique n'était pas le premier essai de Babbage qui avait déjà inventé une "machine à différence". La machine analytique, commandée par le gouvernement britannique pour établir des tables de calcul sans erreur, construite partiellement dans les années 1830 par Babbage et son fils (le moulin, l'imprimante), ne fut cependant jamais achevée. (Compiled from various sources)
Original excerpt : « The operating mechanism can even be thrown into action independently of any object to operate upon (although of course no “result “could then be developed). Again, it might act up upon other things besides number, were objects found whose mutual fundamental relations could be expressed by those of the abstract science of operations, and which should be also susceptible of adaptations to the action of the operating notation and mechanism of the engine. Supposing for instance, that the fundamental relations of pitched sounds in the science of harmonyh 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. »
Source : Hugill, Andrew (2007), "The Origins of Electronic Music", In “Electronic Music - The Cambridge Companion to electronic Music", Edited by Nick Collins & Julio d'Escrivàn Rincón, Cambridge University Press, pp. 11-12.
Source : Menabrea, L.F. (1842), “Sketch of The Analytical Engine Invented by Charles Babbage”, By L. F. MENABREA of Turin, Officer of the Military Engineers, from the Bibliothèque Universelle de Genève, October, 1842, No. 82, With notes upon the Memoir by the Translator ADA AUGUSTA, COUNTESS OF LOVELACE.
Urls : https://www.fourmilab.ch/babbage/sketch.html (last visited ) http://perso.telecom-paristech.fr/~blanchet/SIP_UE_INF227/histoire/prehistoire/babbage.htm (last visited ) http://alexandrebrunet.com/these_chapitre_1_06.html (last visited )

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