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CS04-03 Computer Science Watch

The registers: MAR, MDR, PC and Accumulator

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In this lesson

In this video you'll learn about the registers: MAR, MDR, PC and accumulator for GCSE Computer Science, with worked examples and the mistakes examiners report. By the end you'll be able to state what each of the MAR, the MDR, the Program Counter and the Accumulator stores, and tell an ADDRESS from DATA - saying for each register which of the two it holds and why that is the distinction the mark scheme pays for.

What it covers

  1. 3:39 Two of the four registers give their job away in their own names, if you read them slowly
  2. 5:36 The Program Counter holds the address of the next instruction to be fetched
  3. 8:11 The accumulator holds the result
  4. 10:23 The four registers are not alone inside the processor
  5. 11:28 The same four registers as a matching table, with a definition in each row and a name to write beside it

Key words

For: OCR GCSE J277

On the specification

BoardSpecStatement
OCR GCSE J2771.1.1Architecture of the CPU
For teachers

This GCSE Computer Science lesson teaches the registers: MAR, MDR, PC and Accumulator. By the end, students should be able to state what each of the MAR, the MDR, the Program Counter and the Accumulator stores, and tell an ADDRESS from DATA - saying for each register which of the two it holds and why that is the distinction the mark scheme pays for. It works through four worked examples and the mistakes examiners report.