OCR GCSE (9–1) Computer Science · J277
Specification map
Every section of the J277 specification, and where to practise it.
J277/01 · Computer systems
1.1 Systems architecture 14 questions · 11 key terms
- Purpose of the CPU and the fetch–execute cycle
- CPU components: ALU, CU, cache, registers (MAR, MDR, PC, ACC); Von Neumann architecture
- Performance: clock speed, cache size, number of cores
- Embedded systems
1.2 Memory and storage 30 questions · 17 key terms
- Primary storage: RAM, ROM, virtual memory
- Secondary storage: optical, magnetic, solid state
- Units: bit, nibble, byte, KB, MB, GB, TB, PB
- Binary ↔ denary ↔ hex, binary addition, overflow, binary shifts
- Characters: ASCII, Unicode, character sets
- Images: pixels, colour depth, resolution, metadata, file size
- Sound: sample rate, duration, bit depth, file size
- Compression: lossy and lossless
1.3 Networks, connections and protocols 27 questions · 20 key terms
- LAN and WAN; factors affecting performance
- Client–server and peer-to-peer
- Hardware: WAP, routers, switches, NIC, transmission media
- The internet: DNS, hosting, the cloud
- Star and mesh topologies
- Ethernet, Wi-Fi, Bluetooth, encryption, IP and MAC addressing
- Protocols: TCP/IP, HTTP, HTTPS, FTP, POP, IMAP, SMTP; layers
1.4 Network security 13 questions · 11 key terms
- Threats: malware, social engineering (phishing), brute-force, denial of service, data interception and theft, SQL injection
- Prevention: penetration testing, anti-malware, firewalls, user access levels, passwords, encryption, physical security
1.5 Systems software 8 questions · 7 key terms
- Operating systems: user interface, memory management and multitasking, peripheral management and drivers, user management, file management
- Utility software: encryption, defragmentation, data compression
1.6 Ethical, legal, cultural and environmental impact 9 questions · 8 key terms
- Ethical, legal, cultural, environmental and privacy issues
- Data Protection Act 2018, Computer Misuse Act 1990, Copyright Designs and Patents Act 1988
- Open source and proprietary software
J277/02 · Computational thinking, algorithms and programming
2.1 Algorithms 14 questions · 11 key terms
- Abstraction, decomposition, algorithmic thinking
- Structure diagrams, pseudocode, flowcharts, trace tables
- Searching: binary and linear search
- Sorting: bubble, merge and insertion sort
2.2 Programming fundamentals 22 questions · 16 key terms
- Variables, constants, operators, inputs, outputs, assignment
- Sequence, selection, count- and condition-controlled iteration
- Arithmetic (including MOD, DIV and ^), comparison and Boolean operators
- Data types and casting
- String manipulation, file handling, records, SQL, 1D and 2D arrays
- Sub programs: functions, procedures, local and global variables, random numbers
2.3 Producing robust programs 12 questions · 12 key terms
- Defensive design: anticipating misuse, authentication, input validation
- Maintainability: sub programs, naming, indentation, comments
- Iterative and final testing; syntax and logic errors; normal, boundary, invalid and erroneous test data
2.4 Boolean logic 8 questions · 4 key terms
- AND, OR and NOT gates
- Truth tables
- Logic diagrams with up to three inputs
2.5 Programming languages and IDEs 9 questions · 8 key terms
- High-level and low-level languages
- Translators: compiler, interpreter, assembler
- IDE features: editors, error diagnostics, run-time environment, translators
Full specification: ocr.org.uk