SMS Plus is a Sega Master System and Game Gear emulator for PlayStation Portable.
Changes:
20% speedup in emulation speed with new 8-bit video rendering
Option to turn off FM emulation (an additional 48% improvement in emulation speed – all games now play at 100% speed with VSync enabled)
Various small bug fixes
Source
This article is over 2 years old — the linked page may have changed, moved, or been taken over since then.