EEPROM, or Electrically Erasable Programmable Read-Only Memory, is a type of non-volatile memory used in computers and electronic devices to store small amounts of data that must be saved when power is removed. Unlike traditional ROM (Read-Only Memory), the data stored in EEPROM can be erased and reprogrammed using electrical charge.
How EEPROM Works
EEPROM is made up of arrays of floating-gate transistors that store bits of data through a process known as Fowler-Nordheim tunneling. When an electrical charge is applied, electrons can be added or removed from the floating gate, thereby altering the stored data. This process allows for selective erasure and reprogramming of memory blocks.
Erasure and Reprogramming
- Erasure: EEPROM can erase data byte-by-byte or block-by-block. This fine level of granularity distinguishes EEPROM from other types of erasable programmable memory like EPROM (Erasable Programmable Read-Only Memory), which requires exposure to ultraviolet light to erase contents.
- Reprogramming: Data can be written to EEPROM at any time by applying an electrical charge to the appropriate memory cells.
Types of EEPROM
There are two primary types of EEPROM based on the interface through which they communicate with the rest of the system:
- Serial EEPROM: Uses a serial communication protocol like I²C (Inter-Integrated Circuit) or SPI (Serial Peripheral Interface) for low-speed, low-power applications.
- Parallel EEPROM: Uses a parallel interface for higher speed, larger data transfer applications.
Historical Context
The development of EEPROM dates back to the 1970s when semiconductor engineers sought a memory type that could retain data without power (non-volatile) and still allow for data modification. The precedent ROM technologies did not provide this flexibility, leading to the creation of EEPROM in 1978 by George Perlegos and team at Intel.
Applications of EEPROM
EEPROM is highly versatile and used in various applications such as:
- Embedded Systems: Storing configuration settings or program code.
- Consumer Electronics: Devices like digital cameras, portable media players, and smart cards.
- Computers: BIOS storage and firmware for different peripherals.
- Industrial: Equipment requiring frequent firmware updates or configuration changes.
Comparisons to Related Technologies
EEPROM vs. Flash Memory
While EEPROM and flash memory are both types of non-volatile memory, they differ in a few key aspects:
- EEPROM: Byte-wise erasable and rewritable. Typically offers endurance of around 1,000,000 write/erase cycles.
- Flash Memory: Block-wise erasable which results in faster write speeds for larger data sets but lower endurance, usually around 10,000 to 100,000 write/erase cycles.
EEPROM vs. EPROM
- EPROM: Requires ultraviolet light for erasure and must be removed from the circuit for the process. Provides greater storage capacity but is less convenient for frequent updates.
- EEPROM: Electrically erasable without the need for removal from the circuit, making it more suitable for applications requiring easily updateable non-volatile storage.
FAQs
Can EEPROM lose data?
How long does data last in EEPROM?
Is EEPROM faster than flash memory?
References
- “Introduction to EEPROM.” Microchip Technology Inc.
- “EEPROM Technology and Applications,” Intel Corporation.
- Nelson, Paul A. “‘Nonvolatile Memories: A Tutorial Review.” IEEE Transactions on Electron Devices, 1994.
Summary
EEPROM (Electrically Erasable Programmable Read-Only Memory) represents a critical technology for non-volatile memory, offering the flexibility of electrical erasure and reprogramming. Its unique properties make it indispensable in a myriad of applications ranging from consumer electronics to embedded systems, enabling the retention and modification of data even without power supply.
