Understanding Mobile Phone Memory: NOR vs NAND Flash

As we know, memory is a very essential component of a mobile phone. We can categorize memory into two main parts: read-only memory and read-write memory. There is a third type referred to as hybrid memory. Memory is used to store data in different forms such as audio, video, and text, for different purposes.

EPROM, PROM, and MASKED are read-only type of memories. DRAM, SRAM, and SDRAM are read-write type of memories.

NVRAM, FLASH, and EEPROM are the most widely used hybrid memories in consumer electronic devices.

The main flash memory types are NOR and NAND.

NOR Flash Memory

Following are the specifications or attributes of NOR flash memory:

• Capacity: 1MB-32MB
• Performance: Very slow erase (about 5 seconds), slow write, Fast read
• Reliability: Standard
• Erase cycles: 10,000 to 100,000
• Life Span: Less than 10% the life span of NAND
• Interface: Full memory interface
• Access method: Random
• Ease of use (Hardware): Easy
• Full system integration: Easy
• Ideal usage: Code storage - limited capacity due to price in high capacity. May save limited data as well. Some example applications are home appliances, low-end set-top boxes, low-end mobile handsets, and PC BIOS chips.

NAND Flash Memory

Following are the specifications or attributes of NAND flash memory:

• Capacity: 16MB to 512MB
• Performance: Fast erase (approx. 3msec), Fast write, Fast read
• Reliability: Low
• Erase cycles: 100,000 to 1,000,000
• Life Span: Over 10 times more than NOR
• Interface: I/O only, CLE, ALE, and OLE signals must be toggled.
• Access method: Sequential
• Ease of use (Hardware): Complicated
• Full system integration: It is Hard and a simplistic SSFDC driver may be ported.
• Ideal usage: Data storage only due to complicated flash management. Code will usually not be stored in raw NAND flash. Some example applications are PC Cards, Compact Flash, MP3 players, and Digital Cameras.