Ken Shirriff retrofitted Douglas Engelbar’s 1960s era keyset from his famous “Mother of All Demos” to connect to USB so that it can be used with today’s computers.

We love Ken Shirriff projects, and Ken Shirriff seems to love Teensy too, if the number of our boards we’ve seen used in his various retrocomputing restoration projects are anything to go by. Ken apparently managed to get a loan of one of the original “keyset” devices from Douglas Engelbart’s famous “Mother of All Demos,” during which the concept of a computer mouse and GUI were introduced to the public for the first time. That the keyset was also introduced to the public for the first time at the event is perhaps less worthy of mention, since it didn’t catch on in the same way as some of the other demonstrated tech which we now take for granted. While chorded keyboards are still a thing (particularly among stenographers), and we’ve even shared a Teensy 4.1-powered recreation of Engelbart’s chording keyset on the blog before, it’s certainly a niche device, and Ken even concludes his blog post by saying that he found it hard to use, both physically and mentally. But the cool thing is that he made it work, so let’s focus on that!

Ken’s project is based around the Teensy 3.6’s ability to act as both USB device (connecting to the host PC) and USB host (for connecting a standard USB mouse, required to get the full range of outputs, by being pressed in conjunction with the keyset keys). The Teensy is connected to the keyset’s standard DB-25 connector, with a 1kOhm pull-up resistor on one of the lines, in addition to the Teensy’s own onboard pull-ups on each. Code was added to pass through mouse input, except when used in conjunction with the keyset, as well as output the resultant characters as if it were a normal keyboard. Ken goes into glorious detail on the background of the device and its famous demo on his blog, and has shared the code on GitHub. While he may not have fallen in love with the keyset workflow, we are enamoured with the incredible journey he took to reach that conclusion.