This key facts covers MAR vs MDR - Quick Comparison 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 6 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 vs MDR - Quick Comparison
| Feature | MAR | MDR |
|---|---|---|
| Stands for | Memory Address Register | Memory Data Register |
| Holds | Address (WHERE) | Data (WHAT) |
| Connected to | Address Bus | Data Bus |
| Direction | One-way (to memory) | Two-way (to/from memory) |
Memory Trick
MAR = Memory Address Register (A for Address - WHERE)
MDR = Memory Data Register (D for Data - WHAT)
A comes before D in the alphabet, just like you need to know the ADDRESS before you can get the DATA!
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)