15C functions that can be cancelled with 'null' (quiz)

[brouhaha]

(10-14-2024 12:08 PM)J-F Garnier Wrote:  Can you find the 10 generic operations and the 83 key sequences ?

This prompted me to find the microcode that displays "null". It probably would have been easy to capture a trace in Nonpareil (or another simulator), and work backwards, but I just scanned the source code for more instructions that write to the two hardware LCD registers (0x09 and 0x0a). Special display like Error, running, and null don't go through the normal display formatting code, but get written as bitmaps directly to the hardware.

The subroutine used to wait for the key release is at 0x13b8, with the timing constant 8 loaded by "lc 8" at 13ba. If the key isn't released in time, it falls into the code at 0x13c1 that displays "null".

The 0x13b8 subtrouine is called from just two places in the matrix operation code. I haven't really dug into the matrix operations yet. At some point I want to study the LU decomposition code.