Last time, I assembled a Python object representing a Rigol oscilloscope. Manipulating the object communicates with the scope over the network. But my original goal was to build a little GUI window… ...

The standard Python interpreter uses the GNU Readline library and makes it easy to recall what you've previously typed. The up and down arrow keys allow you to move up and down through your input.

Back in the glorious era of character LCDs and non-standard mounting boxy cute servers, you could get a 16×2 display and five arrow keys on a Sun machine, and with help of a little bespoke ...