Hollerith card (nonfiction): Difference between revisions
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Later designs standardized the coding. These cards had ten rows, each row assigned a digit value, 0 through 9, and 45 columns. This provided for a field (adjacent columns) to represent multi-digit numbers that tabulators could sum, instead of their simply counting cards. | Later designs standardized the coding. These cards had ten rows, each row assigned a digit value, 0 through 9, and 45 columns. This provided for a field (adjacent columns) to represent multi-digit numbers that tabulators could sum, instead of their simply counting cards. | ||
Hollerith's 45 column punched cards are illustrated in [[Comrie (nonfiction)]]'s | Hollerith's 45 column punched cards are illustrated in [[Comrie (nonfiction)]]'s The application of the Hollerith Tabulating Machine to Brown's Tables of the Moon. | ||
== Nonfiction cross-reference == | == Nonfiction cross-reference == | ||
Revision as of 05:56, 16 December 2015
A Hollerith card ("punched card", etc.) is a piece of stiff paper that contain either commands for controlling automated machinery or data for data processing applications.
Both commands and data are represented by the presence or absence of holes in predefined positions.
History
Herman Hollerith was awarded a series of patents in 1889 for mechanical tabulating machines. These patents described both paper tape and rectangular cards as possible recording media.
The card shown in U.S. Patent 395,781 of June 8 was preprinted with a template and had hole positions arranged close to the edges so they could be reached by a railroad conductor's ticket punch, with the center reserved for written descriptions.
Hollerith was originally inspired by railroad tickets that let the conductor encode a rough description of the passenger:
"I was traveling in the West and I had a ticket with what I think was called a punch photograph ... the conductor ... punched out a description of the individual, as light hair, dark eyes, large nose, etc. So you see, I only made a punch photograph of each person."
Use of the ticket punch proved tiring and error prone, so Hollerith invented a pantograph (nonfiction) "keyboard punch" that allowed the entire card area to be used. It also eliminated the need for a printed template on each card: a master template was used at the punch; a printed reading board could be placed under a card that was to be read manually.
Hollerith envisioned a number of card sizes. In an article he wrote describing his proposed system for tabulating the 1890 U.S. Census, Hollerith suggested a card 3 inches by 5½ inches of Manila stock "would be sufficient to answer all ordinary purposes."
The cards used in the 1890 census had round holes, 12 rows and 24 columns. A reading board for these cards can be seen at the Columbia University Computing History site.
At some point, 3 1⁄4 by 7 3⁄8 inches (82.550 by 187.325 mm) became the standard card size.
Hollerith's original system used an ad-hoc coding system for each application, with groups of holes assigned specific meanings, e.g. sex or marital status.
His tabulating machine had up to 40 counters, each with a dial divided into 100 divisions, with two indicator hands; one which stepped one unit with each counting pulse, the other which advanced one unit every time the other dial made a complete revolution. This arrangement allowed a count up to 10,000.
During a given tabulating run, each counter was typically assigned a specific hole. Hollerith also used relay logic to allow counts of combination of holes, e.g. to count married females.
Later designs standardized the coding. These cards had ten rows, each row assigned a digit value, 0 through 9, and 45 columns. This provided for a field (adjacent columns) to represent multi-digit numbers that tabulators could sum, instead of their simply counting cards.
Hollerith's 45 column punched cards are illustrated in Comrie (nonfiction)'s The application of the Hollerith Tabulating Machine to Brown's Tables of the Moon.
Nonfiction cross-reference
Fiction cross-reference
External links
- Punched card @ Wikipedia