ROM

ROM stands for Read Only Memory. It is a type of internal memory stores data and instructions permanently.

• The data stored in ROM can only be read but new data or instructions cannot be written into it.
• When the power is turned off the instructions stored in ROM are not lost. So we call it as non-volatile memory.
• Used to store frequently used instructions and data to control basic input and output operations.
• Data is either modified in extreme difficulty or not at all.

Different Types of ROM :

PROM :

• PROM stands for Programmable Read Only Memory. It can write data once and cannot modify the burnt data in the chip.
• To write data into PROM you need a special device called PROM programmer or PROM burner.
• The difference between a PROM and ROM is that a PROM is manufactured as a blank memory, where as ROM is programmed during manufacturing.

EPROM :

• EPROM stands for Erasable Programmable Read Only Memory. It can rewrite the data over the old data, but you cannot keep the old data.
• So once you burn the new data into the ROM chip the old data is gone.
• The UV lights used to remove the content. It more expensive than PROM.

EEPROM :

• EEPROM stands for Electrically Erasable Programmable Read Only Memory.
• It is a special type of PROM that can be erased by exposing it to an electric charge.
• We can changes or edit the current data in the chip and still keep the data. But they are much expensive.

Advantages of ROM :

• Non-volatile in nature.
• Cheaper than RAM.
• Cannot be accidentally changed.
• Its contents are always known and can be verified.