Source Tree Structure

The cmucl source tree has subdirectories for each major subsystem:

assembly/: Holds the CMU CL source-file assembler, and has machine specific subdirectories holding assembly code for that architecture.
clx/: The CLX interface to the X11 window system.
code/: The Lisp code for the runtime system and standard CL utilities.
compiler/: The Python compiler. Has architecture-specific subdirectories which hold backends for different machines. The generic subdirectory holds code that is shared across most backends.
hemlock/: The Hemlock editor.
lisp/: The C runtime system code and low-level Lisp debugger.
pcl/: cmucl version of the PCL implementation of CLOS.
tools/: System building command files and source management tools.