Mezzano – An operating system written in Common Lisp
Very impressive.<p>Since the demise Lisp machines, there have been several attempts at developing a Lisp-based operating system which didn&#x27;t deliver anything: LispOS, Tunes, and Loper; and one successful attempt at getting Lisp to run on the bare metal: Movitz.<p>Lisp was its own operating system on the original Lisp machines developed at MIT, and this evolved into Genera at Symbolics.   Is this the case here?<p>I notice that Mezzano has files.   Files are inherited from operating systems running non image-based languages.   They&#x27;re alien to Smalltalk, where everything is just stored in the image (or world, in Lisp parlance).   This could also be done in Lisp.   Text files could be replaced by long strings contained in the world.   Hypertext, provided tags are balanced, could be stored as lists.   When the system is shut down, and periodically beforehand, the world is written to disk.<p>You can go further, by using a single address space.    Particularly large blocks of text which don&#x27;t fit into RAM, and so have to be stored on disk, can be addressed by treating the disk as an extension of RAM.   You can even go further on 64 bit machines by treating the entire contents of the internet as an extension of RAM.<p>I once wrote a small bare-metal Lisp interpreter in x86 assembler, which ran off a 1.4Mb floppy on an old laptop.   The hardest part was writing the floppy disk driver, which has to handle frequent hardware errors.   USB drivers are many times harder and I didn&#x27;t attempt that.   If the Mezzano developer(s) succeeded, I&#x27;m even more impressed.