OCR GCSE COMPUTER SCIENCE
Paper 1: Computer Systems
J277/01 - Full aesthetic + exam-focused revision pack
Systems architecture Memory + storage
Networks + protocols Security + software
Ethics, law + impacts
Includes diagrams, worked calculations, scenario tips, retrieval practice and answers.
,OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 2
How to use this pack
Big revision-guide style notes for OCR GCSE Computer Science J277/01
Paper facts Specification map
Component: J277/01 Computer Systems. 1.1 Systems architecture
Written paper: 1 hour 30 minutes. 1.2 Memory and storage
80 marks, worth 50% of the GCSE. 1.3 Computer networks, connections and protocols
Non-calculator. All questions are mandatory. 1.4 Network security
Question styles: multiple choice, short response and extended 1.5 Systems software
response.
1.6 Ethical, legal, cultural and environmental impacts
Best revision method
Exam answer rule
1. Read a page and cover it.
Define the keyword, explain the effect, then apply it to the
2. Brain-dump the key terms from memory. scenario.
3. Try the practice questions without notes. For compare questions, use both sides. For recommend
questions, choose one option and justify it using the scenario.
4. Mark in a different colour and fix weak points.
5. Revisit calculations until the method feels automatic.
What is not required but still easy to accidentally overlearn
You do not need the detailed transfer of data between every register at every stage of the fetch-execute cycle.
You do not need the component parts inside magnetic, optical or solid-state storage.
You do not need to memorise ASCII/Unicode character codes.
You do not need to know how Ethernet, Wi-Fi or Bluetooth protocols work internally.
You do not need the names/functions of each TCP/IP layer for Paper 1, but understanding the idea of layers is useful.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 2
,OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 3
Exam command words and answer style
Use these to turn knowledge into marks
Command What to do Answer shape
State / identify Give a short fact or name. Cache stores frequently used data/instructions.
Describe Say what it is or what happens. Usually needs detail but not Virtual memory uses part of secondary storage as if it were
a full reason. RAM.
Explain Give a point plus a reason/effect. Use because, so, More cache can improve performance because the CPU can
therefore. access frequent data faster than RAM.
Compare Discuss similarities/differences between two things. RAM is volatile whereas ROM is non-volatile.
Mention both.
Recommend Choose the best option for a scenario and justify it. Use an SSD because the laptop needs durability and fast boot
time.
Evaluate / Give advantages and disadvantages, then a judgement. Cloud storage is convenient, but it depends on internet access;
discuss for the school it may still be best because files can be shared
easily.
Grade 9 sentence starters Common mark losses
This would improve performance because... Saying cache 'stores data' without saying it is
frequently/recently used data/instructions.
However, this depends on...
Forgetting that RAM is volatile and ROM is non-volatile.
In this scenario, the best choice is... because...
Saying encryption stops interception. It does not stop
A limitation of this method is... interception; it makes intercepted data unreadable without the
key.
This reduces risk by...
Writing 'better' without explaining speed, capacity, cost,
reliability, etc.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 3
, OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 4
1.1 - Systems architecture
CPU architecture, CPU performance and embedded systems
Von Neumann idea: instructions and data are stored in memory.
RAM
CU ALU
Data moves between CPU, RAM and storage.
CPU
Registers Cache
Secondary storage
Purpose of the CPU Von Neumann architecture
The CPU is the processor. It executes program instructions and Instructions and data are stored in the same main memory.
processes data.
A stored program is fetched from memory, decoded and
It repeatedly performs the fetch-decode-execute cycle. executed by the CPU.
It coordinates other hardware through control signals and uses The CPU uses registers such as the MAR, MDR, Program
registers/cache to work quickly. Counter and Accumulator.
Must-know difference
Address = location in memory. Data = the actual value or instruction stored at that location. The MAR stores an address; the
MDR stores data.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 4
Paper 1: Computer Systems
J277/01 - Full aesthetic + exam-focused revision pack
Systems architecture Memory + storage
Networks + protocols Security + software
Ethics, law + impacts
Includes diagrams, worked calculations, scenario tips, retrieval practice and answers.
,OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 2
How to use this pack
Big revision-guide style notes for OCR GCSE Computer Science J277/01
Paper facts Specification map
Component: J277/01 Computer Systems. 1.1 Systems architecture
Written paper: 1 hour 30 minutes. 1.2 Memory and storage
80 marks, worth 50% of the GCSE. 1.3 Computer networks, connections and protocols
Non-calculator. All questions are mandatory. 1.4 Network security
Question styles: multiple choice, short response and extended 1.5 Systems software
response.
1.6 Ethical, legal, cultural and environmental impacts
Best revision method
Exam answer rule
1. Read a page and cover it.
Define the keyword, explain the effect, then apply it to the
2. Brain-dump the key terms from memory. scenario.
3. Try the practice questions without notes. For compare questions, use both sides. For recommend
questions, choose one option and justify it using the scenario.
4. Mark in a different colour and fix weak points.
5. Revisit calculations until the method feels automatic.
What is not required but still easy to accidentally overlearn
You do not need the detailed transfer of data between every register at every stage of the fetch-execute cycle.
You do not need the component parts inside magnetic, optical or solid-state storage.
You do not need to memorise ASCII/Unicode character codes.
You do not need to know how Ethernet, Wi-Fi or Bluetooth protocols work internally.
You do not need the names/functions of each TCP/IP layer for Paper 1, but understanding the idea of layers is useful.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 2
,OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 3
Exam command words and answer style
Use these to turn knowledge into marks
Command What to do Answer shape
State / identify Give a short fact or name. Cache stores frequently used data/instructions.
Describe Say what it is or what happens. Usually needs detail but not Virtual memory uses part of secondary storage as if it were
a full reason. RAM.
Explain Give a point plus a reason/effect. Use because, so, More cache can improve performance because the CPU can
therefore. access frequent data faster than RAM.
Compare Discuss similarities/differences between two things. RAM is volatile whereas ROM is non-volatile.
Mention both.
Recommend Choose the best option for a scenario and justify it. Use an SSD because the laptop needs durability and fast boot
time.
Evaluate / Give advantages and disadvantages, then a judgement. Cloud storage is convenient, but it depends on internet access;
discuss for the school it may still be best because files can be shared
easily.
Grade 9 sentence starters Common mark losses
This would improve performance because... Saying cache 'stores data' without saying it is
frequently/recently used data/instructions.
However, this depends on...
Forgetting that RAM is volatile and ROM is non-volatile.
In this scenario, the best choice is... because...
Saying encryption stops interception. It does not stop
A limitation of this method is... interception; it makes intercepted data unreadable without the
key.
This reduces risk by...
Writing 'better' without explaining speed, capacity, cost,
reliability, etc.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 3
, OCR GCSE Computer Science J277/01 - Paper 1 Computer Systems Revision Pack | page 4
1.1 - Systems architecture
CPU architecture, CPU performance and embedded systems
Von Neumann idea: instructions and data are stored in memory.
RAM
CU ALU
Data moves between CPU, RAM and storage.
CPU
Registers Cache
Secondary storage
Purpose of the CPU Von Neumann architecture
The CPU is the processor. It executes program instructions and Instructions and data are stored in the same main memory.
processes data.
A stored program is fetched from memory, decoded and
It repeatedly performs the fetch-decode-execute cycle. executed by the CPU.
It coordinates other hardware through control signals and uses The CPU uses registers such as the MAR, MDR, Program
registers/cache to work quickly. Counter and Accumulator.
Must-know difference
Address = location in memory. Data = the actual value or instruction stored at that location. The MAR stores an address; the
MDR stores data.
Use with the official OCR J277 specification and your teacher's guidance. This is a revision aid, not an official OCR resource. 4
