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GCSE

Computer Science

Unofficial Practice Paper: J277/01: Computer Systems

General Certificate of Secondary Education

Mark Scheme for June 2026 [Practice Paper]

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© 2026 gcsecomputerscience.co.uk Practice Suite
June 2026 Practice Paper (Section A)
Question Answer / Indicative Content Mark Guidance
1 (a) 1 mark per point:
  • Coordinates the activities of the CPU [1]
  • Manages the fetch-execute cycle // Decodes instructions [1]
 2 TV: Sends signals.
1 (b) (i) MAR: Stores the address [1] of the memory location where data is to be read from or written to [1].
(ii) MDR: Stores the actual data or instruction [1] that has been fetched from memory or is waiting to be written [1]. 		4 Reject J276 terminology (e.g. PC to MAR transfer).
1 (c) 1 mark per step:
  • The address is sent from the MAR to memory [1]
  • The instruction/data at that address is copied to the MDR [1]
  • The Control Unit (CU) decodes the instruction [1]
  • The instruction is performed/executed (e.g. load/store) [1]
 4 Award 4 marks for a clear technical description of the stages.
2 (a) 1 mark per characteristic:
  • Built into a larger device/system [1]
  • It has a limited or specific function [1]
 2 Any two valid points.
2 (b) 1 mark per justification (max 4):
  • Lower power consumption [1]
  • Higher reliability (fewer complex components) [1]
  • Cheaper to produce specialised hardware in bulk [1]
  • Smaller physical size to fit inside signal housing [1]
 4 Must apply to the traffic signal scenario.
June 2026 Practice Paper (Section A Continued)
Question Answer / Indicative Content Mark Guidance
3 (a) 1 mark per technical difference:
  • RAM is volatile (data lost on power loss) [1], whereas ROM is non-volatile [1]
  • RAM is read-write (data can be changed) [1], whereas ROM is read-only [1]
 4 Must provide both sides of the difference for full marks.
3 (b) 1 mark per point:
  • The OS identifies that the physical RAM is full [1]
  • Area of secondary storage allocated as temporary memory [1]
  • Inactive data moved from RAM to secondary storage [1]
  • Space freed in RAM for active program data [1]
  • Data swapped back to RAM when needed by CPU [1]
  • Allows more apps to run than physical RAM capacity [1]
 6 BOD: "Thrashing" explanation.
4 (a)
  • 12,000 characters * 1 byte (8-bit) = 12,000 bytes [1]
  • 12,000 / 1,000 [1]
  • 12 [1]
  • KB [1]
 4 Full marks for correct answer with units. Base-10 (1,000) required.
4 (b) 1 mark per row:
  • 3 GB: 3,000 MB [1]
  • 3 TB: 3,000 GB [1]
  • 3 MB: 3,000,000 Bytes [1]
  • 30,000 Bytes: 30 KB [1]
 4 Check grid alignment in exam paper.
5 (a) 1 mark per justification (max 4):
  • No moving parts - more durable during patrol movement [1]
  • Faster read-write speeds - essential for HD video recording [1]
  • Lower power consumption - extends battery life [1]
  • Lighter weight - practical for wearable use [1]
 4 Link to "body-camera" context.
5 (b)
  • Characteristic: Capacity [1]
  • Reason: Large files (video) require enough space for full shift [1]
 2 Accept Cost or Reliability if justified.
June 2026 Practice Paper (Section B)
Question Answer / Indicative Content Mark Guidance
6 (a) Bandwidth: Amount of data transferred per second [1]. Low bandwidth causes stuttering sensor data/video [1].
Latency: Time delay for packets [1]. High latency causes delay in real-time control [1]. 		4 AO2: Must link to "drones" or "sensors".
6 (b) Wireless NIC [1] and Wireless Access Point // Router [1]. 2 1 mark per component.
7 (a)
  • IP is assigned by router [1]; MAC is fixed by manufacturer [1]
  • IP identifies location [1]; MAC identifies physical hardware [1]
 4 Accept differences in format (Denary vs Hex).
7 (b) Sequence: 3, 1, 4, 2 [2 Marks]. (1 mark for 2-3 correct). 2 Sequence check.
8 (a) FTP (Uploading) [1], HTTPS (Web access) [1], SMTP (Email) [1]. 3 1 mark per protocol.
8 (b) Allows developers to work on one part without affecting others [1]. 1 Accept: Interoperability.
9 (a) Packets captured over wireless [1]; Attacker uses packet sniffer [1]; Confidential data read if unencrypted [1]. 3 Mechanics of interception.
9 (b) Entering malicious SQL code into a website input form [1]; to bypass security / view or delete database records [1]. 2 Must mention input form and database impact.
June 2026 Practice Paper (Section B Continued)
Question Answer / Indicative Content Mark Guidance
10 1 mark per point:
  • Simulates a real-world cyber-attack [1]
  • Identifies vulnerabilities/weak points [1]
  • Attempts to exploit weaknesses to test depth of breach [1]
  • Produces a report with recommended fixes [1]
  • Allows proactive securing of the network [1]
 5 Terminology focus: "Penetration testing".
11 (a)
  • Acts as a translator/interface between hardware and OS [1]
  • Allows OS to understand/control hardware specific commands [1]
  • Ensures OS remains independent of hardware changes [1]
 3 Focus on "Interface" role.
11 (b) User Interface [1], Memory/Multitasking [1], File Management [1]. 3 1 mark per function.
12* Mark Band 3 (6-8 marks): Thorough knowledge. Balances Environmental vs Privacy. Links stakeholders explicitly. Reference to DPA 2018 is clear and accurate. Clear logical structure.
LevelDescription
3Balanced discussion. Detailed stakeholder analysis. Clear DPA 2018 links.
2Reasonable knowledge. Clear application. One-sided discussion.
1Basic list. Unsupported assertions. Weak context link.

Indicative Content:

  • Ethical: Public safety vs surveillance culture. Protection of environment for future.
  • Legal/Privacy: DPA 2018 principles (Lawful basis, data minimisation). Consent issues for public river users. Transparency (Signage).
  • Stakeholders: Eco-Clean (Profit/Rep), Local Public (Privacy), Government (Policy).
 8 AO2 (4) / AO3 (4)
TOTAL MARKS: 80
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