NAND vs NOR Flash: Types of Flash Memory

There are two primary types of non-volatile flash memory devices in use today: NOR and NAND flash. Below we look at the differences between NAND and NOR flash devices, and explore types of NAND flash, including SLC, MLC, and TLC.

What is NOR Flash Memory?

NOR flash is most often used in applications where individual bytes of data need to be written and read, and is most often used where random access and execute-in-place access techniques are required. As each read access takes the same amount of time, sequential read access is no faster than random access. Erase/program cycles can often be long.

Today’s NOR flash devices are available with capacities in the megabits and low gigabits range. Depending on the device, individual bytes or sectors must be erased before writing data, with erase/program speeds typically below 1 MB/s.

NOR flash has high reliability, and is typically rated to maintain data integrity for 20 years or more.