This is the emulator for the Interlisp-D virtual machine, for a byte-coded Lisp instruction set and some low-level functions for connecting witih Lisp for access to display and disk etc.
There’s a complex system of make files that include all the flags and variables you have to set for each hardware/OS target.
You need to be in the "bin" directory, you need to have "." on your path, you need to do "./makeright x" in order for it to detect the correct OS and then put together the makefile parts that it needs. It will build it in ../.-x (for the .o files) and ../. for the executables.