Contributors to Martin Korth's original documentation:
GPU.TXT by doomed/padua; based on info from K-communications & Nagra/Blackbag
GTE.TXT by doomed@c64.org / psx.rules.org
SPU.TXT by doomed@c64.org / psx.rules.org
CDINFO.TXT by doomed with big thanks to Barubary, who rewrote a large part
SYSTEM.TXT by doomed with thanx to Herozero for breakpoint info
PS_ENG.TXT PlayStation PAD/Memory Interface Protocol by HFB03536
IDT79R3041 Hardware User's Manual by Integrated Device Technology, Inc.
IDTR3051, R3052 RISController User's Manual by Integrated Device Technology
PSX.* by Joshua Walker (additional details in various distorted file formats)
LIBMIRAGE by Rok; info/source code for various cdrom-image formats
psxdev.ru; cdrom sub-cpu decapping
All the contributors to the psx-spx.github.io repo who've helped update, correct and expand this information.