The 32 Mbit to 128 Mbit memory map is shown here only as an example. All SPI flash from ISSI have 4 Kbyte sectors with 32 Kbyte and/or 64 Kbyte blocks. The small sector and block sizes allow efficient code storage during density migration. A common command set is shared to perform similar functions across various product densities, thus reducing the time needed to make software changes.