从计算器具到电子计算机
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Chinese Abacus (13-digits)
http://www.cs.umass.edu/~weems... |
Japanese Soroban (23-digits)
http://www.cs.umass.edu/~weems... |
"Addomoter" -- a late 19th century/early 20th century commercial implementation of Pascal's box. Dials, representing digits of a number, are turned with the stylus, and carries propagate automatically between places.
http://www.cs.umass.edu/~weems... |
"Addiator" an early 20th century addition/subrtraction aid. The stylus is used to slide numbers into place in the central windows. A carry or borrow results when the stylus passes around the hook at the end of the top or bottom slot. Less automatic than the Addometer, (therefore more prone to error) but simpler and less expensive.
http://www.cs.umass.edu/~weems... |
The Layton Arithmometer (Smithsonian Collection). Can perform addition, subtraction, multiplication (through repeated addition) and division (through repeated subtraction). 16 digits of precision with entry of up to 8 digits in a multiplicand.
http://www.cs.umass.edu/~weems... |
A Dietzgen 1734 Slide Rule. The standard "pocket scientific calculator" of the 19th and 20th centuries until the mid 1970's (when it was abruptly replaced in just three years by electronic pocket scientific calculators). Logarithmic scales permitted multiplication and division via analog addition and subtraction (i.e., sliding the scales with repect to each other). Other scales support logarithms, exponents, trigonometric functions, squares, cubes, and corresponding roots. With its rosewood core, teflon bearings, microadjustable hairline and scales, this top-of-the line sliderule offered a whopping three digits of precision (and sometimes four could be reliably interpolated by a skilled user). Note that this presages a shift from being primarily concerned with accuracy toward a desire for speed and ease of use in performing calculations.
http://www.cs.umass.edu/~weems...
berlinchen
3 年, 11 月前说:
这个东西我家里还有一个
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有人认为，世界上第一台对现代计算机产生重要影响的机器是1823年英国发明家和对破译密码十分着迷的查尔斯·巴贝奇（Charles Babbage，1792～1871 English mathematician）发明的一台称为差异引擎（Diference engine; analytical engine，分析机）的机器。这台机器用wheels、gears、cogs（轮子、齿轮、机械部件）等零件构造而成。
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Analytical Engine
Analytical Engine - A portion of the Mill (1871). © Science Museum, London. Science & Society Picture Library. http://www.oldcomputers.arcula... |
A folded slide rule (Smithsonian Collection). The precision of the slide rule could be extended through the use of folded or spiral scales, effectively increasing the length of the scales from about a foot (30 cm) to as much as 30+ feet (~10 m). Accuracy of 5 or 6 digits was possible, and use was much faster than looking up functions in printed tables. High performance computing, ca. 1900.
As computations become more complex, human error creeps into the following of algorithms and the input and output of data. Babbage begins to solve this problem with the difference engine, as it can carry out a preset series of steps and stamp its results directly onto printing plates. The operator is freed from handling the numbers and can devise more complex algorithms. Accuracy again improves. http://www.cs.umass.edu/~weems... |
The Scheutz Difference Engine, 1853. (Smithsonian Collection). This is one of two built, and was used by the Dudley Observatory in Albany, NY, for computing ephemerides. The other was used by the Royal Observatory, London, for similar purposes and for calculating insurance actuarial tables.
Once numbers and computations are separated from each other, algorithms can take a major leap in complexity by employing symbolic quantities. This is the same as going from multiplication and addition to algebra. It is no coincidence that the time of Babbage also saw a revolution in how mathematicians approached algebra. This lead quickly to the analytical engine. However, it was never completed and this new era really only got underway as tabulating machines (a la Hollerith) became more sophisticated. Once the technology made an automatic calculator truly feasible (e.g. ENIAC) the designers again quickly saw the need for a machine that could be programmed to operate on symbolic quantities (EDVAC). http://www.cs.umass.edu/~weems... |
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