MMSPlus is one of the best (IMO the best) Sega Master System and Sega Game Gear emulators for the PSP.
Some of MMSPlus 1.1's features:
Full speed emulation (even with the psp underclocked to save battery in many cases)
The ability to overclock the master systems cpu to get rid of slowdown that existed even on the original console.
An option to crop the blank bar down the left of the screen that exists but is not seen when an original console is played on a tv. Most other emulators will show this bar (seen in some games but not others) and your stuck with an annoying line down the side of the display.
An absolutely stunning UI (menu) with MANY options.
Installation:
Connect your PSP to a PC with a USB cable and put the PSP in USB mode.
Extract the zip archive.
Browse inside the newly created folder 'MMSPlus1.1' and you will find 2 folders 'MMSPlus' and 'MMSPlus%', as well as a readme text file (please read that).
If you are running firmware 1.5: Copy the 2 folders and place them in X:\PSP\GAME (X being the drive letter of your PSP).
If you are running one of Dark_Alex's custom firmwares: Copy the folders to X:\PSP\GAME150 (X being the drive letter of your psp). If this doesn't work then try copying them to X:\PSP\GAME.
Copy your rom files to X:\PSP\GAME\MMSPlus\roms
Exit USB mode, browse on the PSP's menu to Game/Memory stick and choose MMSPlus.
im new to this. do i need to put games on here? it works but im got lost on the second to last instruction::Copy your rom files to X:\PSP\GAME\MMSPlus\roms. i go to load rom on the psp and then i dont know what to do. there no games to select