The hardware and storage limitations of the PSP (specifically the 1.8 GB capacity of UMD discs) were widely cited as reasons why San Andreas, with its massive three-city map, was never officially ported to the system. Official Releases GTA San Andreas

The search for "GTA San Andreas PSP ISO file download Ristechy" is a wild goose chase. No stable, full version exists. What you will find are scams, malware, or broken fan mods.

If you were to find a legitimate file named GTASA_Ristechy_Beta_v0.9.iso , here is the standard procedure:

: Some "PSP ISO" downloads are actually the official Vice City Stories or Liberty City Stories