This is Alan Synder's portable C compiler, written at the Dynamic Modeling group at MIT. It's released with his permission.

The compiler can trace its root back to Bell Labs, where Snyder visited during 1973 and worked on the C compiler and Yacc. It can target PDP-10, PDP-11, and Honeywell 6000 series machines. It originally ran on ITS, but was later ported to TOPS-20 and WAITS.