FYI, DOSBox can run my demo program from 1992 which uses direct screen access, changing of frequency of the clock timer, calling INT for mouse info, and setting CTRL-BREAK interrupt handler – good stuff! For anyone interested, the GitHub repo is here: https://github.com/Russell-S-Harper/EXPLORE, and …

I think I figured out the key mapping file format. I did a random change so the mapping would be saved, then edited the file directly. For my system, "mod3" for SHIFT doesn't seem to work. Instead of the SHIFT-CTRL-ALT-F5 combination I saw recommended somewhere, I mapped VIDEO to CTRL-"Print Screen …

In Linux, the default for VIDEO CTRL-ALT-F5 opens a login, so it has to be remapped to work with DOSBox. I tried remapping to all kinds of combinations of keys. I can't get it to recognize anything to make the VIDEO work. Whatever I save, the line for VIDEO is empty but the screen output still shows …

I'm not understanding the instructions for the keymapper. I deleted the existing mapping for VIDEO, I think, then I added SHIFT, CTRL, ALT, F5 and saved, but it seems to map to each key separately, so SHIFT runs the video capture, then SHIFT-CTRL turns it off, then SHIFT-CTRL-ALT turns it back on, …