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Herman Hollerith |
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Graduates Columbia School of Mines 1879 |
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Takes job at Census Bureau 1880 |
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Census takes 7 years |
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Leaves in 1884 to build tabulating machine |
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Encodes information on cards – dollar sized |
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Each hole represents attribute – religion,
education, gender |
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Complete circuit turns counter |
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Cards can also be sorted |
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1890 Census completed in 3 years, saved $5
million in costs, even though population grew 13 million |
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Began selling in Europe, to railroads, and to
Federal agencies |
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1911 combined with companies making scales, time
clocks, and coffee grinders.
Company was renamed International Business Machines |
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Information can be represented in two states –
circuit/no circuit |
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Binary representations are simple for machines |
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Simple circuits are cheap to build and easier to
maintain – fewer errors |
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Magnetized/unmag – disks |
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Reflective/un – CDs |
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Hi volt/ low volt – modems |
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Switched/unswitched – logic gates |
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Hi frequency/low - satellites |
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American Standard Code for Information
Interchange – ASCII |
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A = 0100 0001 a = 0110 0001 |
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B = 0100 0010 b = 0110 0010 |
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C = 0100 0011 c = 0110 0011 |
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D = 0100 0100 d = 0110 0100 |
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E = 0100 0101 e = 0110 0101 |
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F = 0100 0110 f = 0110 0110 |
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Notes