OCR · GCSE · J277
Computer Science — Keywords & Key Terms — Definitions Glossary (2026)
OCR GCSE (9–1) Computer Science (J277)
Topic-by-topic keywords, key terms and definitions for precise exam language—separate from our revision checklists (topic coverage) and formula sheets (equations).
Keywords & Key Terms — definitions
Examiner-style keywords and definitions organised by syllabus topic. Terms are tagged Essential (start here), Core (typical exam standard), and Advanced for harder distinctions — tick each row when you can recall it. Your progress is saved in this browser for this list.
OCR GCSE Computer Science (J277)
OCR GCSE Computer Science (J277)
OCR GCSE (9–1) Computer Science (J277)
Aligned to OCR J277: Component 01 (Computer systems — architecture, memory & storage, networks, system security, system software, ethics) and Component 02 (Computational thinking, algorithms and programming — including Boolean logic and data representation).
Mark schemes: OCR mark schemes reward precise computing terminology — name registers exactly (PC, MAR, MDR, CIR, ACC) and quote units correctly (bits, bytes, KB, MB). Algorithm questions: trace tables and pseudocode that match OCR's Exam Reference Language. Examiner reports flag confusion between RAM/ROM, lossy/lossless, and validation/verification.
Active recall: 0 / 36 terms ticked
| Recalled | Topic | Level | Keyword | Definition |
|---|---|---|---|---|
| Systems architecture & the CPU | Essential | CPU | Central Processing Unit — fetches, decodes and executes instructions. | |
| Systems architecture & the CPU | Core | ALU | Arithmetic Logic Unit — performs calculations and logical comparisons. | |
| Systems architecture & the CPU | Core | Control Unit (CU) | Directs operations of the processor; manages the FDE cycle. | |
| Systems architecture & the CPU | Core | Cache | Small, fast memory storing frequently used instructions/data. | |
| Systems architecture & the CPU | Core | Clock speed | Number of FDE cycles per second, measured in Hz. | |
| Systems architecture & the CPU | Core | Von Neumann architecture | Shared memory for instructions and data; CPU with registers. | |
| Systems architecture & the CPU | Advanced | Registers (PC, MAR, MDR, CIR, ACC) | Program Counter, Memory Address/Data Registers, Current Instruction Register, Accumulator. | |
| Systems architecture & the CPU | Advanced | Fetch–decode–execute cycle | PC supplies address to MAR; instruction loaded to MDR then CIR; decoded and executed; PC increments. | |
| Memory, storage & data representation | Essential | RAM | Volatile primary memory holding currently running programs and data. | |
| Memory, storage & data representation | Essential | ROM | Non-volatile memory holding boot/firmware instructions. | |
| Memory, storage & data representation | Core | Virtual memory | Section of secondary storage used as RAM when RAM is full. | |
| Memory, storage & data representation | Core | Secondary storage (HDD/SSD/optical) | Non-volatile long-term storage — capacity, speed and durability vary. | |
| Memory, storage & data representation | Core | Binary / hexadecimal | Base 2 and base 16 — convert via grouping 4 bits per hex digit. | |
| Memory, storage & data representation | Core | Two's complement | Binary representation of signed integers — flip bits and add 1 to negate. | |
| Memory, storage & data representation | Core | ASCII / Unicode | Character encoding standards — Unicode supports more characters using more bits. | |
| Memory, storage & data representation | Advanced | Image file size | width × height × bit depth ÷ 8 (bytes). | |
| Memory, storage & data representation | Advanced | Sound sample rate / bit depth | Samples per second × bit depth × duration ÷ 8 (bytes). | |
| Networks, topologies & protocols | Core | LAN / WAN | Local Area Network (single site) vs Wide Area Network (geographically dispersed). | |
| Networks, topologies & protocols | Core | Star topology | All devices connect to a central switch — robust to single-cable failure. | |
| Networks, topologies & protocols | Core | Mesh topology | Devices interconnected with multiple paths — high reliability, high cost. | |
| Networks, topologies & protocols | Core | Packet switching | Data split into packets routed independently and reassembled. | |
| Networks, topologies & protocols | Core | TCP/IP | Suite governing reliable transport and routing across networks. | |
| Networks, topologies & protocols | Core | HTTP / HTTPS | Web request protocol; HTTPS adds TLS encryption. | |
| Networks, topologies & protocols | Advanced | DNS | Translates domain names to IP addresses via hierarchical lookup. | |
| Algorithms & complexity | Core | Linear search | Check each element in turn — works on unsorted lists; O(n). | |
| Algorithms & complexity | Core | Binary search | Repeatedly halve a sorted list; O(log n). | |
| Algorithms & complexity | Core | Bubble sort | Repeatedly swap adjacent out-of-order pairs — simple but slow. | |
| Algorithms & complexity | Core | Insertion sort | Build sorted portion by inserting each new item into place. | |
| Algorithms & complexity | Advanced | Merge sort | Divide-and-conquer — split, sort, merge; more efficient on large data. | |
| Programming & Boolean logic | Essential | Variable | Named memory location holding a value that can change. | |
| Programming & Boolean logic | Core | Sequence, selection, iteration | Three programming constructs — order, IF/ELSE, loops. | |
| Programming & Boolean logic | Core | Data types (integer, real, Boolean, char, string) | Categories controlling how data is stored and operated on. | |
| Programming & Boolean logic | Core | Procedure vs function | Subroutine without return vs subroutine returning a value. | |
| Programming & Boolean logic | Core | AND / OR / NOT | Core logic gates — used in truth tables and conditions. | |
| Programming & Boolean logic | Advanced | NAND gate | NOT AND — output false only when both inputs true. | |
| Programming & Boolean logic | Advanced | Truth table | Lists every input combination and resulting output for a logic expression. |
Pair this with our revision checklists, formula sheets hub and past paper finder.
Computer Science (J277) — Keywords & Key Terms FAQ
- What is on this OCR GCSE Computer Science keywords and key terms list?
- It is a topic-organised glossary of important computer science terms with short, exam-style definitions aligned to OCR GCSE (9–1) Computer Science (J277) (J277). It is designed for “define”, “state”, “outline” and “explain” questions where precise vocabulary earns marks.
- How should I use this Computer Science glossary alongside past papers?
- Tick terms when you can recall them without reading the answer, then check your wording against mark schemes. Pair vocabulary practice with past papers for GCSE Computer Science (J277) so you apply terms in context.
- Is this the same as a revision checklist or a formula sheet?
- No. Revision checklists help you track which syllabus topics you have covered and your confidence—separate pages on Tutopiya. Formula sheets summarise equations and quantitative relationships. This page is only a definitions and key-terms glossary for Computer Science.
- Can I download this Computer Science keywords and key terms list for free?
- Yes. After a quick free sign-up you can download a UTF-8 CSV (opens in Excel or Google Sheets) or open a print-friendly page and save as PDF. Browsing the list on the page is free.
- Is this Computer Science list aligned to the J277 specification?
- Topic groupings and wording follow OCR GCSE (9–1) Computer Science (J277) for OCR GCSE. Always confirm final learning objectives and any regional options in your official specification and recent examiner reports for your exam session.
- Why focus on definitions instead of full notes?
- Mark schemes reward correct technical terms and clear links between ideas. A compact glossary lets you drill the exact language examiners expect for Computer Science at GCSE, separate from longer notes or topic trackers.