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(1) (Stacker) An earlier real-time compression program from Stac Electronics, Carlsbad, CA. It doubled the disk capacity of a DOS, Windows, Mac or OS/2 computer.

(2) An output bin on a copy or fax machine or other paper feeding device. In the early days of data processing, stackers were found on every punch card machine. Contrast with hopper. See tabulator.

Punch Card Stackers (1960)
Ordering data into sequence required placing the punch cards in the input hopper of the sorter, running them through, removing them from the stackers (arrow) and putting them back in the hopper again. For example, sorting a ten-digit account number required 10 passes through the machine.


A machine that added up numerical data in punch cards. Tabulators were used to prepare invoices, checks and "green-striped" reports as late as the 1970s. Invented by Herman Hollerith in 1890, his tabulator displayed the totals on dials. Subsequent models were able to perform additional arithmetic operations as well as print the results. See Hollerith machine, punch card and continuous forms.

First Tabulator - 1890 U.S. Census
After placing the punch card in the reader and pulling the handle down, the dials incremented, and the card was dropped into the sorting box that opened. (Image courtesy of The Computer History Museum,

A Tabulator in the 1960s
Tabulating machines such as the IBM 407 (left) were used to print millions of reports, invoices and checks. Hollerith's company evolved into IBM, and IBM was always the leading tabulating equipment vendor (see Hollerith machine). (Image courtesy of IBM.)

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