This key facts covers MAR - Memory Address Register within MAR, MDR & Registers for GCSE Computer Science. Revise MAR, MDR & Registers in 3.4 Computer Systems for GCSE Computer Science with 15 exam-style questions and 10 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 4 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
MAR - Memory Address Register
- Purpose: Holds the ADDRESS of the memory location the CPU wants to access
- Connected to: The Address Bus
- Direction: One-way - CPU writes to MAR, which sends to memory
- Contains: A memory address (like a postcode or house number)
- Think: "WHERE do I need to look?"
Real-world analogy
MAR is like the GPS coordinates you type into your sat nav - it tells the system WHERE to go, not what's there.
Practice questions for MAR, MDR & Registers
What does MAR stand for?
Explain the difference between the MAR and the MDR.
Quick recall flashcards
What does MDR hold?
The actual data being transferred (WHAT)
What does MAR hold?
The address of data to be read/written (WHERE)