What’s the Difference Between ROM and NVM? : Emily Rosemary Collins

What’s the Difference Between ROM and NVM?
by: Emily Rosemary Collins
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ROM (Read-Only Memory) and NVM (Non-Volatile Memory) are two types of memory used in computing.

ROM (Read-Only Memory) is a non-volatile memory used mainly for storing firmware, typically written once and not meant for frequent rewriting.

NVM (Non-Volatile Memory) is a broader category of non-volatile memory used for various storage purposes, allowing frequent data writing and erasing.

While both retain data without power, ROM is mainly for system-level software, and NVM encompasses a wider range of storage applications.

ROM (Read-Only Memory)

The earliest microcontrollers used ROM (read-only memory) programmed into the device as part of the processor’s manufacturing. High volume was required to make this worth the cost.

Example ROM (source)
  • Nature: ROM is a non-volatile memory mainly used for storing firmware or permanent software closely tied to hardware. The data stored in ROM remains even after the power is turned off.
  • Usage: Typically, ROM is used to store system-level software that doesn’t need to be modified, like the BIOS in a computer.
  • Write Capability: Traditionally, ROM is written only once during the manufacturing process and cannot be rewritten. However, some modern types of ROM, like EEPROM (Electrically Erasable Programmable Read-Only Memory), can be rewritten, though typically at a much slower pace than RAM.
  • Speed: ROM generally has slower read speeds than volatile memory like RAM.

NVM (Non-Volatile Memory)

Non-Volatile Memory (NVM) retains its information, even when power is removed. NVM covers a wide range of memory technologies, including flash memory, certain types of RAM like Ferroelectric RAM, and indeed, ROM.

  • Nature: NVM, like ROM, retains its data even when power is not supplied. However, NVM is used more broadly for storage purposes and is not limited to firmware.
  • Usage: It includes a wide range of memory types used for various storage purposes, from flash memory in USB drives and SSDs (Solid State Drives) to other forms of memory used in devices for storing user data.
  • Write Capability: Unlike ROM, NVM is designed to allow frequent writing and erasing of data. The ease and speed of writing vary among different types of NVM.
  • Speed: NVM can have varying speeds. For example, SSDs, which use NVM, have faster read/write speeds compared to traditional hard drives but may be slower than volatile memory types like RAM.

In summary, while both ROM and NVM are non-volatile types of memory, ROM is primarily used for firmware and is not typically rewritten, whereas NVM encompasses a broader range of memory types used for general data storage and allows for frequent data writing and erasing.

ROM is a subset of NVM.

December 05, 2023 at 08:49PM
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