What is ROM?
Different Types of ROM
- PROM (Programmable ROM)
- EPROM (Erasable Programmable ROM)
- EEPROM (electrically erasable programmable ROM)
- Flash EPROM
- Mask ROM
PROM (programmable ROM) and OTP
EPROM (erasable programmable ROM) and UV-EPROM
Programming a UV-EPROM
- Its contents must be erased. To erase a chip, remove it from its socket on the system board and place it in EPROM erasure equipment to expose it to UV radiation for 5—20 minutes.
- Program the chip. To program a UV-EPROM chip, place it in the ROM burner (programmer). To burn code or data into EPROM, the ROM burner uses 12.5 volts or higher, depending on the EPROM type. This voltage is referred to as Vpp in the UV-EPROM data sheet.
- Place the chip back into its socket on the system board.
EEPROM (electrically erasable programmable ROM)
Flash memory EPROM
- First, the erasure of the entire contents takes less than a second, or one might say in a flash, hence its name, Flash memory.
- In addition, the erasure method is electrical, and for this reason it is sometimes referred to as Flash EEPROM. To avoid confusion, it is commonly called Flash memory.
The major difference between EEPROM and Flash memory is that when Flash memory’s contents are erased, the entire device is erased, in contrast to EEPROM, where one can erase a desired byte.