SuperFlash® Flash Memory Explained
We all use NOR Flash to load simple boot code, but Flash has one big problem… ERASE time. If you are reflashing the system in the field or running a few system tests on the floor, erasing a whole NOR Flash IC can take… MINUTES…even erasing a few sectors can take 10’s of seconds. That’s why Microchip offers SuperFlash.
http://www.microchip.com/memory