Sources of helpful information used in PS1 emulation(though some of it, especially older compiled information,
is wrong to some degree or incomplete, but it's still useful):

-----------
 Source code
-----------
  PCSX(and derivatives/forks)
  MAME/MESS
  P.E.Op.S
  LR333x0 development header files
  cdrdao
  dvdisaster


-----------
 Homebrew
-----------
  Blade Lib
  psxsdk


-----------
 Documents
-----------
  doomed's PSX documents
  bITmASTER's document
  Neill Corlett's SPU documents
  T.Fujita's SIO documents
  jac's CD-XA document
  "The PlayStation 1 Video (STR) Format" - M. Sabin
  Various PS1 emulator compatibility lists(for identifying problematic games)
  no$psx technical documentation
  SCSI-3 Multimedia Commands Revision 10A
  ECMA-130


-----------
 People
-----------
  ChrlyMac
  Exophase
  mizvekov
  notaz
  pSXAuthor
  smf(blog)
  shalma(forum posts, changelogs)
  drhell's site


-----------
 Books
-----------
  MIPS RISC Architecture - Gerry Kane (1st and 2nd editions)
  MIPS Programmer's Handbook, The

