This key facts covers Types of ROM within RAM and ROM for GCSE Computer Science. Revise RAM and ROM in Memory & Storage for GCSE Computer Science with 15 exam-style questions and 16 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 7 of 10 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 7 of 10
Practice
15 questions
Recall
16 flashcards
Types of ROM
While the name "Read Only Memory" suggests you can never change the data, modern ROM types offer different levels of reprogrammability:
1. Traditional ROM (Mask ROM):
- Data written during manufacturing - cannot be changed EVER
- Used for devices with fixed functionality (simple calculators, old game cartridges)
- Cheapest option for mass production
2. PROM (Programmable ROM):
- Blank when manufactured - can be programmed ONCE by the user
- Uses special programming device to "burn" data permanently
- Once programmed, cannot be erased or changed
- Good for custom firmware that won't need updates
3. EPROM (Erasable Programmable ROM):
- Can be programmed, erased with UV light, then reprogrammed
- Has a quartz window on the chip - expose to UV for 10-20 minutes to erase
- Must remove from circuit to erase (inconvenient!)
- Useful for prototyping and development
4. EEPROM (Electrically Erasable Programmable ROM):
- Can be electrically erased and reprogrammed WITHOUT removing from device
- Can erase/write individual bytes (very flexible)
- Used in modern computer BIOS chips - allows firmware updates!
- Slower write speeds than RAM
- Limited write cycles (~100,000 times per cell)
5. Flash Memory (Type of EEPROM):
- Modern advancement of EEPROM - faster and higher density
- Used in: USB drives, SD cards, SSDs, smartphones, digital cameras
- Can only erase/write in BLOCKS (not individual bytes like EEPROM)
- Non-volatile - keeps data without power
- Much faster than traditional ROM, but slower than RAM
- Limited write cycles but high enough for years of normal use