PROM or programmable ROM (programmable read-only memory) is a computer memory chip that can be programmed once after it is created. Once the PROM is programmed, the information written is permanent and cannot be erased or deleted. PROM was first developed by Wen Tsing Chow in 1956. An example of a PROM is a computer BIOS in early computers. Today, PROM in computers has been replaced by EEPROM.
EEPROM (Erasable Programmable Read Only Memory)，是一種斷電后仍能保留數據的計算機儲存芯片——即非易失性的（非揮發性）。它是一組浮柵晶體管，被一個提供比電子電路中常用電壓更高電壓的電子器件分別編程。一旦編程完成后，EPROM只能用強紫外線照射來擦除。通過封裝頂部能看見硅片的透明窗口，很容易識別EPROM，這個窗口同時用來進行紫外線擦除。可以將EPROM的玻璃窗對準陽光直射一段時間就可以擦除。

EEPROM國際品牌有： Microchip (微芯) ATMEL (愛特美爾) ST Microelectronics (意法半導體) ON Semiconductor (安森美) ROHM Semiconductor (羅姆半導體) Xilinx (賽靈思)
EEPROM國內品牌有：  華虹NEC， 復旦微 ，億存芯科技、 北京兆易、 航順、輝茫微等。其中億存芯是專業從事EEPCOM研發生產廠家，可以完全兼容ST 意法半導體EEPROM全系列產品。