Masked ROM (MROM)
· It contains a pre-programmed set of data and instructions burnt onto the chip during the manufacturing process.
· The information once written cannot be changed.
Programmable ROM (PROM)
· It is manufactured as a blank chip which can be programmed using a special device called a PROM programmer or PROM burner.
· Once programmed, its contents cannot be modified or erased.
Erasable Programmable ROM (EPROM)
· It can be programmed multiple times unlike PROM.
· The chip contents can be erased and re-written by exposing it to strong ultraviolet (UV) light.
Electrically Erasable Programmable ROM (EEPROM)
· It can be programmed multiple times like EPROM.
· Unlike EPROM, the data can be erased and re-written electronically with no need of UV light.
· Selective data can be erased from the EEPROM without erasing the whole chip.
Test your knowledge: What type of ROM is a Flash Memory drive – MROM, PROM, EPROM, EEPROM?