The tabulating machine was an electromechanical machine designed to assist in summarizing information and, later, accounting. Invented by Herman Hollerith, the machine was developed to help process data for the 1890 U.S. Census. It spawned a class of machines, known as unit record equipment, and the data processing industry.
1890 census 
The 1880 census had taken seven years to tabulate, and by the time the figures were available, they were clearly obsolete. Due to rapid growth of the U.S. population from 1880 to 1890, primarily because of immigration, it was estimated that the 1890 census would take approximately 13 years to complete — an immense logistical problem. Since the U.S. Constitution mandates a census every ten years to apportion taxation between the states and to determine Congressional representation, a faster method was necessary.
In the late 1880s Herman Hollerith, inspired by conductors using holes punched in different positions on a railway ticket to record traveler details such as gender and approximate age, invented the recording of data on a machine readable medium. Prior uses of machine readable media had been for lists of instructions (not data) to drive programmed machines such as Jacquard looms and mechanized musical instruments. "After some initial trials with paper tape, he settled on punched cards..." Hollerith used punched cards with round holes, 12 rows and 24 columns. His tabulator used electromechanical relays (and solenoids) to increment mechanical counters. A set of spring-loaded wires were suspended over the card reader. The card sat over pools of mercury, pools corresponding to the possible hole positions in the card. When the wires were pressed onto the card, punched holes allowed wires to dip into the mercury pools, making an electrical contact that could be used for counting, sorting, and setting off a bell to let the operator know the card had been read. The tabulator had 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, counters could be assigned a specific hole or, using relay logic, a of combination of holes, e.g. to count married females. If the card was to be sorted a compartment lid of the sorting box would open for storage of the card, the choice of compartment depending on the data in the card.
Hollerith's method was used for the 1890 census. The cards were coded for age, state of residence, gender, and other information. Clerks used keypunches to punch holes in the cards to enter information from the returns. The census results were "... finished months ahead of schedule and far under budget".
Following the 1890 census 
The advantages of the technology were immediately apparent for accounting and tracking inventory. Hollerith started his own business in 1896, founding the Tabulating Machine Company. In that year he introduced the Hollerith Integrating Tabulator, which could add numbers coded on cards, not just count the number of holes. Cards were still read manually using the pins and mercury pool reader. 1900 saw the Hollerith Automatic Feed Tabulator used in that year's U.S. census. A control panel was incorporated in the 1906 Type 1.
In 1911, four corporations, including Hollerith's firm, merged to form the Computing Tabulating Recording Company (CTR). Tabulators that could print, and with removable control panels, appeared in the 1920s. In 1924 CTR was renamed International Business Machines (IBM). IBM continued to develop faster and more sophisticated tabulators, culminating in the 1949 IBM 407. Tabulating machines continued to be used well after the introduction of commercial electronic computers in the 1950s.
Many applications using unit record tabulators were migrated to computers such as the IBM 1401. Two programming languages, FARGO and RPG, were created to aid this migration. Since tabulator control panels were based on the machine cycle, both FARGO and RPG emulated the notion of the machine cycle and training material showed the control panel vs. programming language coding sheet relationships.
In its basic form, a tabulating machine would read one card at a time, print portions (fields) of the card on fan-fold paper, possibly rearranged, and add one or more numbers punched on the card to one or more counters, called accumulators. On early models, the accumulator register dials would be read manually after a card run to get totals. Later models could print totals directly. Cards with a particular punch could be treated as master cards causing different behavior. For example, customer master cards could be merged with sorted cards recording individual items purchased. When read by the tabulating machine to create invoices, the billing address and customer number would be printed from the master card, then individual items purchased and their price would be printed. When the next master card was detected, the total price would be printed from the accumulator and the page ejected to the top of the next page, typically using a carriage control tape.
With successive stages or cycles of punched-card processing, fairly complex calculations could be made if one had a sufficient set of equipment. (In modern data processing terms, one can think of each stage as an SQL clause: SELECT (filter columns), then WHERE (filter cards, or "rows"), then maybe a GROUP BY for totals and counts, then a SORT BY; and then perhaps feed those back to another set of SELECT and WHERE cycles again if needed.) A human operator had to retrieve, load, and store the various card decks at each stage.
Models and timeline 
Hollerith's first tabulators were used for the U.S. 1890 Census.
The first CTR automatic feed tabulator, operating at 150 cards/minute, was developed in 1906.
The first CTR printing tabulator was developed in 1920.
IBM 301 (Type IV) Accounting Machine: From the IBM Archives:
The 301 (better known as the Type IV) Accounting Machine was the first card-controlled machine to incorporate class selection, automatic subtraction and printing of a net positive or negative balance. Dating to 1928, this machine exemplifies the transition from tabulating to accounting machines. The Type IV could list 100 cards per minute.
IBM 401: From the IBM Archives:
The 401, introduced in 1933, was an early entry in a long series of IBM alphabetic tabulators and accounting machines. It was developed by a team headed by J. R. Peirce and incorporated significant functions and features invented by A. W. Mills, F. J. Furman and E. J. Rabenda. The 401 added at a speed of 150 cards per minute and listed alphanumerical data at 80 cards per minute.
Introduced in 1934, the 405 Alphabetical Accounting Machine was the basic bookkeeping and accounting machine marketed by IBM for many years. Important features were expanded adding capacity, greater flexibility of counter grouping, direct printing of the entire alphabet, direct subtraction and printing of either debit or credit balance from any counter. Commonly called the 405 "tabulator," this machine remained the flagship of IBM's product line until after World War II.
IBM 402 and 403, from 1948, were modernized successors to the 405.
Introduced in 1949, it was later adapted to serve as an input/output peripheral for a number of early electronic calculators and computers. Its printing mechanism was used with the IBM 1130 through the mid-1970s.
The IBM 407 Accounting Machine was withdrawn from marketing in 1976, signaling the end of the unit record era.
See also 
- List of IBM products#Tabulators, Accounting machines
- British Tabulating Machine Company
- Powers Accounting Machine Company
- Powers-Samas Accounting Machines Ltd aka. "Acc and Tab"
- Remington Rand Tabulating Machines
- UNIVAC 1004 80/90 Card Processor
For early use of tabulators for scientific computations see
Notes and references 
- Eames, Charles; Eames, Ray (1973). A Computer Perspective. Cambridge, Mass: Harvard University Press. p. 95. The 1920 date on page 95 is incorrect, see The Columbia Difference Tabulator - 1931
- Columbia University Computing History - Herman Hollerith
- Truedsell, Leon E. (1965). The Development of Punch Card Tabulation in the Bureau of the Census 1890-1940. US GPO. p. 51.
- [-245-] An Electric Tabulating System, The Quarterly, Columbia University School of Mines, Vol.X No.16 (April 1889)
- IBM Archive: Hollerith Tabulator & Sorter Box
- U.S. Census Bureau: Tabulation and Processing
- IBM Tabulators and Accounting Machines
- "Columbia University Computing History - IBM Type 285".
- U.S. Census Bureau: The Hollerith Machine
- IBM Archive: 1906
- "IBM Archives: 1920". IBM.
- Later IBM tabulators provided multiple, small, counters of 2 to 8 positions. When a larger counter was needed multiple counters could be grouped to function as a single counter. For example, a control panel could be wired to group a 4 position and a 6 position counter, forming a 10 position counter.
- Before direct subtraction was available, negative numbers were entered as complements or were listed and totaled in separate columns.
- Bull Gamma 3
- IBM 407 Accounting Machine
Further reading 
- Fierheller, George A. (2006). Do not fold, spindle or mutilate: the "hole" story of punched cards. Stewart Pub. ISBN 1-894183-86-X. An accessible book of recollections (sometimes with errors), with photographs and descriptions of many unit record machines. The chapter It all adds Up describes IBM tabulators and accounting machines.
- Hollerith, Herman (December 1894). "The Electric Tabulating Machine". Journal of the Royal Statistical Society (Blackwell Publishing) 57 (4): 678–682. doi:10.2307/2979610. JSTOR 2979610. From (Randell, 1982) ... brief... fascinating article... describes the way in which tabulators and sorters were used on ... 100 million cards ... 1890 census.
- Kistermann, F.W. (Summer 1995). "The way to the first automatic sequence-controlled calculator: the 1935 DEHOMAG D 11 tabulator". Annals of the History of Computing 17 (2): 33–49. doi:10.1109/85.380270.
- Randell (ed.), Brian (1982). The Origins of Digital Computers, Selected Papers, 3rd ed. Springer-Verlag. ISBN 0-387-11319-3. Chapter 3, Tabulating Machines, has excerpts of Hollerith's 1889 An Electric Tabulating System and Couffignal's 1933 Calculating Machines: Their Principles and Evolution.
|Wikimedia Commons has media related to: Tabulating machines|