IBM keyboards were one of the earliest keyboards to make use of capacitive sensing Beam Spring switches, with designs dating back to the early 1970s. The capacitive sensing on the switches is similar to how a touchscreen works--with an anode and a cathode--but instead of your finger touching a screen, there is a small pad under the switch that simulates your finger and increases the capacitance of the electrodes.
This technology eventually gave way to touchscreens and represents a dramatic shift from earlier keyboard and typewriter designs. Beam Springs are unique because when you press down on them, part of the internal mechanism actually inverts and goes up, which is decidedly unusual. As a result, the feel of the switch could be described as being closer to the Selectric typewriter than any other IBM switch since. That was likely the actual goal, because almost every data entry user at the time was familiar with the former.
The keyboard has beautiful double shot keycaps, a split space bar, and a solid steel case, and it weighs roughly 10 pounds. The shift keys are lower than other keys, which is unusual. This keyboard is dramatically clickier and noisier than IBM Model Ms, but for maximum noise, it also has an added solenoid that fires with every keypress, reverberating through the frame.
Such a keyboard would be extremely expensive and impractical to make today. It’s difficult to mass manufacture, and the mechanisms are quite fragile to create and hand-assemble. As a reference, the target price for this keyboard in the 1970s was around $1,500 (or about $8,000 today), rendering it an amazing antique unlikely to be replicated.
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