PSX Documentation ProjectPlaystation Document
With over a year's worth of work, the PSX Documentation Project is just about THE guide to the Playstation. After discussing the history of the PSX, it goes into great detail about the memory, CPU, GPU, GTE, MDEC, SPU, the bios itself, the syscalls and all the peripherals. It even includes an exhaustive appendix with the number systems, BIOS calls, GPU command listings and a glossary of terms. If you're the average Joe wanting to see what's inside the grey box, or an advanced programmer looking at developing an emulator or creating a ROM, this is the document you need.
Author: Joshua Walker
Author's website: http://www.execpc.com/~halkun/PSX/index.html