I've had a lot of requests for information on how to rip PSFs. I haven't had time to write a definitive guide, but here is a short explanation. It pertains to Playstation PSF1 only.
Here is everything you need to do PSF2 CSL rips with no programming knowledge necessary. Plus, there's a few modules to help you get started on custom driver rips, if you're more experienced.
Updated 28 November 2003 - New, improved version of FAKESIF.IRX included.
This document assumes you know Z80 assembly and are at least familiar with the basics of Capcom's QSound system. Include sample code from Street Fighter Alpha 2. Doesn't cover encryption, so is only useful for CPS2 games.