Read Only Memory (ROM)

Read Only Memory can be subdivided into many different categories, such as PROM (Programmable Read Only Memory), EPROM (Erasable and Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read Only Memory). The ROM is a device that is mask programme at the factory by the manufacturer in the last phase of fabrication. It is most often used to a large production runs because the manufacturer charges thousands of dollars for the initial mask.

The PROM is a field programmable device programmed by a machine called PROM burner or PROM programmer. Here, the programming is done only once.

The EPROM has an advantage over the PROM because it can be erased. The EPROM is erased by exposing it to a high-intensity ultraviolet light for approximately 6 to 40 minutes.

The EEPROM is a device that can be programmed and erased electrically. It is often called read mostly memory (RMM) - since it is often used to store data for an extended period of time.

For an example, as soon as we put on the computer, the messages displayed and other devices connected to it are checked by the program inside the ROM, which is called firmware.