As a work around for TradeWars 2 (v11.14 and v11.20) FOSSIL support:
This door game would never call the FOSSIL "get received character"
function (02h) . But I did notice that it was calling the "Keyboard
read" functions. I never implemented the "Keyboard read" functions
(figured the door game could read the keyboard itself if it wanted to),
but appparently TW2 won't ever read the COM port (using function 02h)
unless the Keyboard read function returns AX=0xFFFF (no keyboard data
available). So now, I just do that and TW2 works (with FOSSIL I/O).

Incremented the revision to 26.
Logging the Git branch/hash and other helpful FOSSIL-debug stuff now.