A typewriter is a terrible thing to waste [Hands on]

The paper mentions that a manual typewriter's keyboard makes a perfectly good computer keyboard-with a little bit of hacking. Here's how the computer attached to the typewriter knows which key has been pressed: When a letter is typed, the key's metal support bar touches a single contact on the board. Meanwhile, the microcontroller is stepping a single logic "l" down the row of shift register pins and thus the leaf-spring contacts wired to them, letting the microcontroller detect the circuit made between the typewriter and the board. Then, like any other USB keyboard controller, it sends the appropriate code back tothe PC. A few strategically placed magnets and reed switches detect the shift key, carriage returns, and whatever the user wants to configure.