These easy, trimmed down charts will help you find out if your PS3 is downgradable and what the lowest firmware that it can be downgraded to.
To see the full chart head over to the PS3dev wiki.
Please note that by clicking the above links, you will be leaving Civilization
Update v1.20 : - Added support for custom firmware 4.76 CEX (Ferrox) and Custom Firmware 4.76.x Rebug REX.
SYSCALL must be disabled using a tool like PSNpatch, SEN Enabler, web MAN MOD or another application in addition to the spoof !!!
NOTE: You must disable this spoofer if you're upgrading to 4.80 CFW or later.
Details: psx-place forum - Fixed constant write for pointer codes (type 6 codes).
Pointer codes were only once written and you had to activate them everytime from ingame xmb with start button. Add : For PS2 and PS1 the main icon (aka 'ICON0') is loaded at the path of the game. Note : (1) It use the included Wide Screen pnach collection from PCSX2.