1. ROM: Read-Only Memory
    1. Chip functionality had to be designed prior to manufacture
    2. Chips were 'built' with the program hard-wired inside them
    3. Each run of chips was a custom manufactured batch
    4. Chips are application-specific
    5. Cannot be changed once manufactured
  2. PROM: Programmable Read-Only Memory
    1. Single design for the memory chip
    2. Contents of the chip can be 'flashed in' later.
    3. Flashing is permanent (Fuse or antifuse)
  3. EPROM: Eraseable Programmable Read-Only Memory
    1. Single design for the memory chip
    2. Flashable like PROM
    3. Erased via UV light (unlike PROM)
    4. Becomes unusable after too many flashes
  4. EEPROM: Electrically Eraseable Programmable Read-Only memory
    1. Single design for the memory chip
    2. Contents can be flashed in later
    3. Contents can be erased and reflashed
    4. Many more 'flashings' than EPROM
    5. Doesn't require a UV Erasing device

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