Erasable programmable read only memory

Erasable Programmable Read-Only Memory (EPROM)

Date invented	1971
Invented by	Dov Frohman
Connects to	Computer Microcontroller Memory device

Erasable Programmable Read-Only Memory (EPROM) is a type of non-volatile memory used in computers, microcontrollers, and other digital logic circuits. EPROM provides a means for storing digital data in a permanent form, though unlike ROM, it can be erased and reprogrammed using ultraviolet (UV) light.

History

EPROM technology was invented by Dov Frohman in 1971 while he was working at Intel. The development of EPROM was significant because it allowed data stored in the memory to be erased and reprogrammed, which was not possible with traditional ROM.

Functionality

EPROM chips are made from MOS (metal-oxide-semiconductor) technology. The data on an EPROM chip is stored in floating-gate transistors, which are MOS transistors that have an additional gate called the "floating gate." The floating gate can store an electrical charge and thus maintain the state of the transistor without power.

To write data to an EPROM, a higher voltage than usual is applied to the floating gate, causing electrons to be "injected" through the oxide layer onto the floating gate. Once the charge is stored, the data remains intact even when the power supply is removed.

To erase the data stored in an EPROM, the chip is exposed to strong ultraviolet light. The UV light causes the electrons on the floating gate to become excited and eventually disperse, effectively "resetting" the chip to its blank state.

Applications

EPROMs are used in various applications where data must be stored permanently but may need to be updated periodically, such as in firmware storage for computers and other electronic devices. The ability to update the firmware or software without replacing the memory chip has made EPROM a critical technology in the evolution of digital electronics.

Advantages and Disadvantages

The main advantage of EPROM is its flexibility in being reprogrammable. This makes it ideal for prototyping and testing digital designs before final production. However, the need for UV light to erase the chip and the relatively slow write speeds compared to other types of memory are considered disadvantages.

See Also

• PROM
• EEPROM
• Flash memory
• Memory device