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Inside Card Sorters of 1920s – Data Processing with Punched Cards and Relays

Inside Card Sorters of 1920s – Data Processing with Punched Cards and Relays


IBM Type 82 punched card sorter. From 'IBM Card Equipment Summary'.

IBM Type 82 punched card sorter. From IBM Card Equipment Summary, 1957.

Before computers existed, businesses carried out data processing tasks by using punched cards and electromechanical equipment such as the card sorter. Card sorters remained useful in the computer era and were still used until punched cards finally died out. Sorters used a variety of interesting technologies from mechanical brushes and cams to relay logic and thyristor tubes. Even though punched cards are now obsolete, their influence is visible whenever you use 80-column text.[5]The Computer History Museum in Mountain View demonstrates a working card sorter weekly, so stop by if you’re in the area. Thanks to the IBM 1401 restoration team and the Computer History Museum for access to the sorters.

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Notes and references

[1] Herman Hollerith is one of the key inventors of the data processing industry. He founded a company that, after various mergers, became IBM in 1924. Hollerith’s 1889 patent 395,782 (Art of Compiling Statistics) describes how to record data on punched cards and then generate statistics from those cards. Hollerith also gave his name to the Hollerith constants used for character data in old FORTRAN programs.[2] Using a sorter to order cards for a report is roughly analogous to a database ORDER BY operation. Sorting cards so subtotals can be computed is analogous to a GROUP BY operation.

[3] Strictly speaming, radix sort on n records tames O(m*n) time if the field is m characters wide. But since punched cards limit m to 80 columns, m can be considered a constant factor, maming radix sort linear.

[4] The Type 80 card sorter was invented by Eugene Ford in 1925 and received patent 1,684,389 (Card feeding and handling device). The card sorter has many interesting features so it’s a bit surprising that the patent covers just the “picker” that feeds cards through the sorter one at a time. The drawing below is from the patent, and can be compared with the photo of the sorter.

IBM card sorter, from patent 1,684,389.


IBM card sorter, from patent 1,684,389 (Card feeding and handling device), 1928.

You might wonder how the Type 80 card sorter was introduced in 1925 when the modern punched card was developed a few years later in 1928. The first Type 80 sorters worked with 45-column cards and were slightly modified in 1928 to support 80-column cards. The changes were minor since the cards remained the same size; the brush mechanism needed to have 80 stops instead of 45.


[5] For detailed information on the sorters (including wiring diagrams) see the Reference Manual and the IBM Customer Engineering Manual.

[6] The industrial design section is based on The Interface: IBM and the Transformation of Corporate Design. This book gives a detailed history and analysis of IBM’s industrial design.

[7] A primitive but complex mechanism is used to select one thyratron tube as each row is read. Although the 12 thyratrons are physically installed in a line, they are electrically wired in a 3×4 grid. Four mechanical cams select a grid row; one cam is activated at a time. You’d expect three cams to select a grid column, but there are six. The problem is a single mechanical cam can’t turn the switch on and off fast enough. The solution is to use two cams in series with staggered operation. The first cam closes the circuit to select the thyratron, while the second cam opens a short time later to de-select the thyratron. By using two cams and two switches, each switch has more time to open and close. As a card is read, the cams open and close, selecting each thyratron in sequence to hold the value (hole or no hole) for that card position. After the card column has been read into the thyratrons, the hole pattern is transferred to 12 relays and the thyratrons are reset for the next card.

[8] IBM’s relays are discussed in detail in Commutation and Control, IBM Relays Reference Manual and IBM Relays Customer Engineering.

[9] The story of why parts of the US used 25 Hertz power instead of the standard 60 Hertz is interesting. Hydroelectric power was developed at Niagara Falls starting in 1886. To transmit power to Buffalo, Edison advocated DC, while Westinghouse pushed for polyphase AC. The plan in 1891 was to use DC for local distribution and (incredibly) compressed air to transmit power 20 miles to Buffalo, NY. By 1893, the power company decided to use AC, but used 25 Hertz due to the mechanical design of the turbines and various compromises. In 1919, more than two thirds of power generation in New York was 25 Hertz and it wasn’t until as late as 1952 that Buffalo used more 60 Hertz power than 25 Hertz power. The last 25 Hertz generator at Niagara Falls was shut down in 2006. See 25-Hz at Niagara Falls, IEEE Power and Energy Magazine, Jan/Feb 2008 for details.


Original article by Ken Shirriff at his blog.


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