Djgpp – 32bit DOS Development System
delorie.com
delorie.com
DJGPP + Allegro was great in it's time
Nowadays I think there are much more recent versions of GCC that can be made to target DOS. I don't know the work involved, but a guy named bisqwit had some tools.
So dad got a phone bill that turned him purple, and grounded me for 2 weeks. I couldn't care less as I finally had a C compiler worth using. Thanks, Delorie.