Eprom

EPROM (Erasable Programmable Read-Only Memory) is a type of memory chip that retains its data when its power supply is switched off. Unlike other types of read-only memory (ROM), EPROM can be erased and reprogrammed. This makes it a versatile component in various electronic applications.

History

EPROM was invented by Dov Frohman in 1971 while working at Intel. The invention of EPROM was a significant advancement in the field of semiconductor memory, providing a more flexible and reusable form of memory compared to traditional ROM.

Structure and Function

An EPROM chip is composed of an array of floating-gate transistors. Each transistor can store a bit of data, which is represented by the presence or absence of an electrical charge on the floating gate. The data stored in an EPROM can be erased by exposing the chip to ultraviolet light through a transparent quartz window on the top of the chip. This process resets the floating gates, allowing the chip to be reprogrammed.

Programming and Erasing

Programming an EPROM involves applying higher-than-normal voltage to the chip, which causes electrons to tunnel through the gate oxide and become trapped on the floating gate. This process is known as hot-carrier injection. To erase the data, the chip is exposed to UV light, which provides enough energy to release the trapped electrons from the floating gate.

Applications

EPROMs are used in a variety of applications, including:

• Firmware storage
• Microcontroller programming
• Embedded systems
• Prototyping and development

Advantages and Disadvantages

Advantages

• Reusability: EPROMs can be erased and reprogrammed multiple times.
• Non-volatility: Data is retained even when the power is turned off.
• Flexibility: Useful for development and testing purposes.

Disadvantages

• Erasing process: Requires exposure to UV light, which can be inconvenient.
• Limited erase cycles: The number of times an EPROM can be erased and reprogrammed is finite.
• Slower access times compared to other types of memory.

Related Technologies

• EEPROM (Electrically Erasable Programmable Read-Only Memory)
• Flash memory
• PROM (Programmable Read-Only Memory)
• NVRAM (Non-Volatile Random-Access Memory)

See Also

• Memory chip
• Read-only memory
• Microcontroller
• Firmware
• Embedded systems