This is a removable plugboard for the IBM 402 accounting machine set up to compute "Gross Profit Detail." Connecting two holes in the panel with a wire completed a circuit that passed data from one component of the machine to another. Data could be output by punching new cards or sending it to a printer.

Eleanor Kolchin, later one of the first computer programmers, describes setting up a plugboard for a tabulating machine shortly after World War II:

“If I wanted to multiply, say, 12 times 15, I would punch a 'one' and a 'two' into the first column of a card and the second column of a card, then in the third column I would put another 'one' and in the fourth column I would put a 'five.' So the first two spots would be 'one' and 'two' and that would go into place on the plug board that shows it is the multiplier, and then the third and fourth spots on the card would go to a place that showed it was the multiplicand. And then there was a third slot that was to be the result, and that would punch the answer into whichever column on the card you wanted to put it in [the cards had 80 columns in all]. And then you would need six wires to complete that." (Eleanor Kolchin, The Face Of A 'Computer' From 1946, Interview by Bianca Bosker, Huffpost, Feb. 1, 2013. Retrieved March 14, 2020.)