Structure: NOR Flash is organized as a series of memory cells that are connected in parallel. Each memory cell is made up of a transistor and a floating-gate MOSFET (metal-oxide-semiconductor field-effect transistor), which can store a charge. The charge on the floating gate determines whether the cell represents a binary 1 or 0.

  Read operation: NOR Flash is designed for random access, meaning that individual bytes can be read directly without the need for a read-modify-write cycle. The read operation is performed by sending an address to the memory, which activates the corresponding memory cell. The charge on the floating-gate MOSFET is then read and interpreted as a binary value.

  Write and erase operation: NOR Flash uses a mechanism called Fowler-Nordheim tunneling to write and erase data. To write data, a high voltage is applied to the control gate of the memory cell, which causes electrons to flow through the thin oxide layer and onto the floating gate. To erase data, a high voltage is applied to the substrate of the memory cell, which causes the electrons to tunnel out of the floating gate and onto the substrate.

  Endurance and retention: NOR Flash has a high endurance, meaning that it can withstand a large number of write and erase cycles before it becomes unreliable. It also has good data retention, meaning that it can maintain its stored data for a long time without needing to be refreshed.

  Applications: NOR Flash is often used in embedded systems, where it is used to store boot code, firmware, and other critical code. It is also used in devices that require high performance and reliability, such as networking equipment, automotive systems, and medical devices.