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

Sorters and IBM’s industrial design

As you may have noticed from the photos above, IBM’s industrial design changed drastically from the early sorters.[6] The Type 80 sorter is an example of IBM’s early hardware, built of cast iron in a “Queen Anne” style with curved cabriole legs. The mechanisms and motor of the Type 80 sorter are visible. By the time of the Type 82 sorter, IBM was using industrial design firms and had an “understated Art Deco aesthetic”. Note the curved, sleek enclosure of the Type 82 sorter, and its shiny horizontal metal trim. The Type 83 and Type 84 sorters are more boxy, without the decorative trim, moving closer to the dramatic modernist style of IBM’s computers of the 1960s.

The technology inside the sorter

This section looks inside the Type 83 sorter and describes how it was implemented using tube and relay technology. Unlike earlier sorters, the Type 83 sorter read the entire column before selecting the bin for the card. This permitted more complex processing, such as detecting erroneous cards with multiple punches. The sorter used 12 vacuum tubes to store the holes in the column as they were read. Electromechanical relays implemented the decision logic to select the bin, and then solenoids activated the chute blade for that bin.Removing the panel from the end of the sorter shows most of the mechanism (below). At the top is the feed hopper where cards are fed into the sorter. On the right, a pulley connects the feed mechanism to the motor. Mechanical cams (behind clear plastic) are also driven by the motor. Below the power switch and fuses, the 12 vacuum tubes are barely visible. Two rows of rectangular relays provide the control logic for the sorter. Behind the relay panel is the power supply for the sorter.

There is no clock for the sorter; all timing is relative to the position of the driveshaft, with one 360° rotation corresponding to one clock cycle. Sixteen cams (behind plastic near the top of the sorter) open and close switches at various points in the cycle to provide electrical signals at the right times.

The photo below shows the brush and the chute blade selection solenoids. On the right, you can see the pointer that indicates the selected column. The brush itself is below the pointer. In the middle are the 12 oblong coils that select the bin. These coils push the selected chute blades down (using the levers at the front), allowing the card to pass between the selected blades.