No more dropped frames, the solution was...
1) LPT2MIDI allows lower delay (only times 4 in al, dx) as opposed to SBMIDI.
2) The timer is reset every 69th frame.
3) OPL3 delay (1+3 times in al, dx) is used.
I released the sources...
1) https://github.com/eigenco/LPT2MIDI
2) https://github.com/eigenco/supaplex
