3 threads/loader.S: From MIT class code but heavily modified.
5 threads/io.h: Also from MIT class code but less modified.
7 threads/synch.c: More or less transliterated from Nachos' synch.cc.
8 filesys/filesys.c: Ditto.
9 filesys/filehdr.c: Ditto.
11 All other files written by me, although inspiration is often due to
12 Nachos or in some cases Linux.