CMUCL is a free Common Lisp implementation, originally developed at Carnegie Mellon University.
CMUCL runs on most Unix-like platforms, including Linux and BSD; there is an experimental Windows port as well. Steel Bank Common Lisp is derived from CMUCL. The Scieneer Common Lisp is a commercial derivative from CMUCL.
The earliest implementation predates Common Lisp and was part of Spice Lisp, around 1980. In 1985 Rob MacLachlan started re-writing the compiler to what would become the Python compiler and CMUCL was ported to Unix workstations such as the IBM PC RT, MIPS and SPARC. Early CMUCL releases did not support Intel's x86 architecture due to a lack of registers. CMUCL strictly separated type-tagged and immediate data types and the garbage collector would rely on knowing that one half of the CPU registers could only hold tagged types and the other half only untagged types. This did not leave enough registers for a Python backend.
After CMU canceled the project (in favor of a Dylan implementation using some of CMUCL's compiler base) maintenance has been taken over by a group of volunteers. By 1996 this group was making regular releases on its own infrastructure.
(Goebel Reeves)
Go to sleep, you weary hobo
Let the towns drift slowly by
Can't you hear the steel rail hummin'?
That's a hobo's lullaby
Do not think about tomorrow
Let tomorrow come and go
Tonight you're in a nice warm boxcar
Safe from the all the wind and snow
I know your clothes are torn and ragged
And your hair is turnin' gray
Lift your head and smile at trouble