Background: History And Development, Continued

The second type of Flash is NAND Flash, invented in 1989 by Toshiba, and positioned as a cheaper and faster alternative to NOR Flash. Toshiba was also the first company to use the name Flash. In comparison to NOR, NAND technology offered ten times the number of write cycles, and higher speeds in both the save and delete processes. The memory cells in NAND memory are only half as large as those in NOR memory. This results at least in a theoretical cost advantage for NAND: the smaller cell size allows larger capacities to be used in a given space, which means both a lower price for the buyer and a higher margin for the manufacturer.

NAND Flash from Infineon

According to the Flash developer M-Systems, NAND deletes data within four milliseconds, while NOR needs five seconds for the same process. The reason for this is the larger block sizes of NOR - from 64 to 128 kBytes. In contrast, NAND accesses blocks of between 8 and 32 kBytes. Because of its better performance, NAND is normally used in memory cards - such as CompactFlash, SmartMedia, SD, MMC, xD, and PC cards - as well as the now very popular USB sticks.