This key facts covers MDR - Memory Data 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 5 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
MDR - Memory Data Register
- Purpose: Holds the actual DATA being transferred between CPU and memory
- Connected to: The Data Bus
- Direction: Two-way - can receive data FROM memory OR send data TO memory
- Contains: Instructions or data values
- Think: "WHAT did I find?" or "WHAT do I want to store?"
Real-world analogy
MDR is like a delivery person's hands - they can carry a package FROM the warehouse to you, or carry something FROM you back to the warehouse.
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 MAR hold?
The address of data to be read/written (WHERE)
What does MDR hold?
The actual data being transferred (WHAT)