Spoiler:
- Loads of keys, including weird function-like keys and special purpose run/pause/continue/execute program keys..
- Nice key caps. They're really thick double shot spherical caps with Cherry crosspoint mounts.
- A rotary encoder!
- The internal hardware and protocol, HP's HIL, are interesting. It was designed to allow multiple devices to daisy chain. There are mice, of course, and numpads, a single rotary encoder, a bank of six rotary encoders (!!), and even a converter box to allow PS/2 keyboards and mice to connect.
I'm not selling anything (but I did buy one). I just think they are really interesting devices and wanted to highlight their current availability.