top of page
OCR GCSE Computer Science Exam Questions
1.1 Systems Architecture
1.1 question 25
Alicia has designed a computer using Von Neumann architecture.
Describe the purpose of two registers used by this architecture.
4
MARKS
Mark scheme
MAR: Stores address/location where data/instruction will be read/written/fetched.
MDR: Stores data/instruction read from memory / to be written to memory / from address in MAR.
(Also credit PC – next/current instruction address; Accumulator – stores results; CIR/IR – holds current instruction.)
MDR: Stores data/instruction read from memory / to be written to memory / from address in MAR.
(Also credit PC – next/current instruction address; Accumulator – stores results; CIR/IR – holds current instruction.)
Exam guidance
Up to 2 per register (name + accurate purpose). ‘MAR stores address’ alone is insufficient; likewise ‘MDR stores data’ alone.
bottom of page