With this latest set of changes, we have the curses-based version of the emulator more or less complete for interactive use.  We’ve put in more error handling and fixed some bugs.

Soon, we’ll put in the programming mode, which will be a bit more complex than these minor patches.   After that, we’ll start extending the calculator beyond the abilities of the physical calculator.  That means allowing complex numbers, multi-character strings as labels and memory registers, perhaps hexadecimal output for integers.

This change also adds memory registers to the display.

Here’s what happens when you try to take the square root of -1 right now, before complex numbers are permitted:

Here is the display with some memory registers loaded, and display digits set to 5:

The current code is in the git repository under the tag v2014-11-28.