@rain1 This looks like it could be useful in bootstrapping. While Jeremy is doing hex, my concept was converters to/from binary and ASCII in general and for an assembler. The firmware might be a FSM looping input from the user into memory until a termination symbol shows up. It passes control to it. Converters, a basic interpreter for adding/removing/gotoing programs in memory, and ability to display internal state might be the start. The result is a few programs can be inputted manually in binary, next few are in text, and system becomes more usable with each step. Finally, code for saving to write-once storage (i.e. antifuse) is put in, hash checked, and activated for the image in memory. It loads on reboot.
That’s the hardcore version for doing it within the system itself with no dependencies and just basic I/O. Gotta use the real machine in that concept: no cheating with hex allowed. ;)