What is NOR Flash Memory and How Does it Work?| NOR vs NAND Flash

NOR flash memory is a type of non-volatile Flash memory that is used in almost all electronic devices to store data. It has been widely used since the early 1990s and usually comes in the form of ICs. Due to its several benefits such as fast read/write speed, compact sizes, and very low power consumption, it is very familiar to all electronic device manufacturers.

In this article, we will discuss all about What is NOR flash memory, How NOR flash memory works, Types of NOR flash memory, its features, Advantages and Disadvantages of NOR flash memory, and many other concepts. We will also explain Applications of NOR flash memory with examples in everyday life. So, stay tuned and read the full article carefully.

What is Flash Memory?

Flash memory is a non-volatile, programmable, and high-speed chip-based storage technology that retains data even without a constant power supply. With the advantages of NVRAM (Non-Volatile Random Access Memory), Flash combines the qualities of ROM and RAM. It has the ability to be electronically erasable and programmable (EEPROM), as well as the ability to read data quickly.

In the past, embedded systems have used ROM (EPROM) as their storage device. With the advent of Flash, ROM (EPROM) has been completely replaced in embedded systems like those used in Embedded IC. Flash can now be used as a hard drive (USB flash drive, solid-state drive), as well as a storage bootloader for operating systems and program code.

NOR Flash and NAND Flash are the two main types of flash memory, each of which has distinct benefits and disadvantages. NOR flash is typically used in cell phone memory, Internet of Things (IoT) devices, medical devices, and scientific instruments. While NAND Flash is used in Digital cameras, SD memory cards, USB drives, Tablets, and Computers. In some cases, digital devices like smartphones and computers use both NOR and NAND Flash- for example, NAND Flash in solid state hard drive (SSD) and NOR Flash in the operating system BIOS.

The programming technologies of FPGA include Anti-fuse, SRAM, and EEPROM/Flash, while With the aid of CMOS EPROM, EEPROM, flash memory, and SRAM programming technologies, CPLD creates programmable logic devices that are very dense, swift, and energy-efficient. Flash memory can be divided into two types: NAND Flash and NOR Flash.

What is NOR Flash Memory?

In 1988, Intel invented NOR flash technology, which fundamentally altered the way EPROM and EEPROM were used. NOR flash memory is made up of FGMOS or FGMOSFET. Each FGMOS is an electronic cell that can store either 0 or 1. In NOR flash memory, these cells are arranged in a parallel manner so that we can read the contents of this memory very fast.

The reading of NOR flash is the same as that of regular SDRAM, i.e., it can be read and written randomly based on the address. Additionally, the user can run the code put in NOR Flash directly, which can lower the cost of SRAM by reducing its capacity.

It is also a non-volatile memory, which means it can store data permanently even when it is not connected to the battery or any power source. NOR memory is used where an individual byte is addressed instead of a whole page. It is mostly used to store programs, operating systems BIOS, and other crucial information due to its fast reading speed.

History of NOR Flash Memory

NOR Flash Memory was first developed by a well-known Japanese company Toshiba in 1988. Dr. Fujio Masuoka was the man behind it, who was a team leader and engineer who developed NOR Flash Memory. When they discovered flash memory, semiconductor technology started the boom in that era. Many electronic devices such as digital cameras, MP3 players, camcorders, and any audio/video are developed using this flash memory. Dr. Fujio Masuoka’s research replaced the big and slow magnetic storage devices, that have changed the world forever and created a revolution in the electronics industry.

How does NOR Flash Work?

Below fig. explains the Working of NOR Flash Memory.

The FGMOS (Floating Gate Metal Oxide Semiconductor Field Effect Transistors) is the fundamental component of NOR flash memory. The Floating Gate is an area found in every transistor. The electrons contained within this region can either be trapped or released. These electrons are trapped by switching the transistor and turning on. Each transistor is referred to as a memory cell since it can represent either 0 or 1.

Types of NOR Flash Memory

NOR Flash Memory is mainly categorized into two types Parallel NOR Flash and Serial NOR Flash.

• Parallel NOR Flash

In this particular type of NOR Flash, a parallel address bus is used by the memory controller to address the memory. Either an 8-bit bus or a 16-bit bus can be used for the parallel NOR. The Parallel NOR Memory with extra storage space can be addressed using a 16-bit address bus.

• Serial NOR Flash

Serial NOR is also known as SPI NOR, here the acronym SPI stands for “Serial Peripheral Interface”. It has Pages and sectors, where sectors are larger than pages. A sector is a block of memory whose entire contents can be erased at once, While data is being written on the pages.

Features of NOR Flash Memory

• Non-Volatile: Non-volatile storage of NOR flash memory, refers to the ability of storage devices to use this type of flash memory to preserve data without the need for a battery or another form of power source. It can store the data without corrupting it for a very long time.
• Dense Memory: Although NOR flash is a dense memory, meaning a small and compact size of chip can hold a lot of data. However, it is not produced for commercial use because its production cost is higher than that of NAND flash.
• Re-programmable: Because NOR flash memory can be reprogrammed, it is utilized in a variety of products, including USB drives, cell phones, and medical equipment. Additionally, this memory can also be used to build gadgets or storage facilities.
• Random Access Interface: The Random Access Interface of NOR Flash Memory allows us to target a specific area of the memory rather than reading it sequentially from the beginning. As a result, this feature makes it more flexible to utilize during the workflow.
• Faster Read Time: In NOR Flash Memory, the time required to read the stored data is much less. This is the reason why applications that make use of random access or execute-in-place approaches need NOR flash memory.

Uses of NOR Flash Memory

NOR Flash Memory is used in:

• Static Random Access Memory (SRAM)
• Medical devices
• USB devices
• Cell phones
• Scientific instruments
• Devices with execute-in-place approaches
• Other smart electronic devices

Advantages and Limitations of NOR Flash Memory

Difference between NOR Flash and NAND Flash

NOR Flash	NAND Flash
It is organized in parallel of memory cells	NAND flash memory has a faster read speed
It has a lower density of data.	It is organized in a series of memory cells
It is organized in parallel with memory cells	NAND flash memory can survive fewer erase/write cycles before starting to degrade than NOR
NOR flash memory can survive more erase/write cycles before starting to degrade than NAND	It has a faster random access time than NAND
It is used in applications that require frequent read and write operations.	It is commonly used in high-density storage applications.

Comparison chart of NOR Flash vs NAND Flash

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