I was in college for most of my Atari ST days. Since I used C a lot at school for many projects (Unix with gcc typically), I naturally started collected C compilers for the ST.
In the ST world, Laser C was probably the most popular C compiler, at least in the late 80s. This was a newer version of the Megamax C compiler that came to the ST from the Macintosh back in 1986 or so.
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Atari 8-bit BASIC programs
Atari ST software