CS378W, History of Computing
Week 4, Weekly Report
Due 2004 Sep 16
Babbage's Analytical Engine
Bryant Tang
2004 Sep 16
The 1800s ushered in yet another era of advancement in the area of computing. One of the largest steps forward was the concept of a general purpose computing device, which was first conceived by the British mathematics professor Charles Babbage in 1834 (4) and described in 1837 (2). With contributions from Ada Lovelace and L. F. Menabrea (1), the analytical engine existed only as a series of designs, for no actual physical specimen was ever built due to "financial and technical issues" (2). However, it is generally believed that the engine would ultimately have functioned correctly (2), earning it its place in computing history.
The analytical engine was based upon one of Babbage's earlier creations, the difference engine, a specialized computer that was limited to performing only specific mathematical functions (2). While working on the difference engine, he realized that "the whole of arithmetic now appeared within the grasp of mechanism", leading him to pursue his vision of a general computing device. He likens the new concept to that of a Jacquard loom, which allowed artists to weave "any design which the imagination of man can conceive" (3). Similarly, the analytical engine would be capable of computing all sorts of mathemetical functions, without being restricted by its architecture; an "unlimited number of laws". (3)
It was broken down into two basic parts - the store where "all the variables to operated upon, as well as those quantities which have arisen from other operations, are placed" and the mill, where "the quantities about to be operated upon are brought" (3). This sets a precedence for future innovations in the field of computing, for most future designs would have some form of 'store' (memory chips, a disk drive, etc.) and a 'mill' (a processor), a concept which remains till this day. To operate the machine, one would have to use two sets of punch cards. The first set is to "direct the nature of the operations to be performed", telling the analytical engine to use a specific mathematical operation. (3) The second set would then be required to feed the variables to the engine, "the order in which they are required to be acted upon" (3). Output was to be handled by punch cards, for one of Babbage's requirements was that it would be equipped with a "mechanism for punching on blank pasteboard cards or metal plates the numerical results of any of its computations". (3)
Menabrea, who first met Babbage while the latter was travelling in Italy, wrote a description of the analytical engine (1). A highly detailed passage, it talks more about the actual mathematical concepts upon which the analytical engine was to be based, as opposed to a description of the actual hardware implementation (as in Babbage's autobiography). It was later translated into English by Ada King, Countess of Lovelace (2). Apart from a direct translation of Menabrea's text, she also provided a lengthy set of notes based upon the translated text. This came as a result of her personal interest in Babbage's analytical engine, something she allegedly became interested in ten years earlier (2). It is widely believed that she may be the first computer programmer in the world, due to the annotations (1) she wrote regarding the analytical engine. (2). Though some people have called that into question, that title is still recognized by most as being held by her.
It was this particular machine that would herald the age of general purpose computing devices, the precursor to what we see in today's computers. Though it was never actually constructed as a physical device, the analytical engine set the foundation upon which later generations would build upon.
Notes
1. L. F. Menabrea, "Sketch of the Analytical Engine," http://www.fourmilab.ch/babbage/sketch.html (Fourmilab, accessed 2004 Sep 15).
2. "Analytical Engine," http://en.wikipedia.org/wiki/Analytical_engine (Wikipedia, accessed 2004 Sep 15).
3. Charles Babbage, "Passages from the life of a Philosopher," http://www.fourmilab.ch/babbage/lpae.html (Fourmilab, accessed 2004 Sep 15).
4. "Analytical Engine," http://www.sciencemuseum.org.uk/on-line/babbage/page5.asp (Science Museum, accessed 2004 Sep 15).