PSP Custom Firmware 6.37 ME Features
Recovery Menu: accessible when holding R Trigger from a cold boot.
OPNSSMP: lets you run ISOs without decrypting (or patching) EBOOT.BIN if the game’s required firmware is lower than 6.37. Enable this under Recovery Menu -> Advanced -> Advanced Config -> Execute OPNSSMP.bin
See Readme.txt (included) for installation instructions. You’ll require the OFW 6.37 EBOOT too.