OCR AS Level Computer Science Past Papers

OCR AS Level Computer Science (H046) covers the theoretical foundations of computing and the practical skills of algorithm design and programming through two examined components. The specification develops students' understanding of how computers work, how data is represented and processed, and how problems can be broken down and solved algorithmically. Component 1: Computer Principles (H046/01, 1 hour 30 minutes, 70 marks) covers the theoretical foundations: the structure and function of the processor (the fetch-decode-execute cycle, the roles of registers — MAR, MDR, PC, ACC, CIR — the ALU, control unit, and cache memory), primary and secondary storage (RAM, ROM, HDD, SSD, optical media — their characteristics and appropriate uses), data representation (binary and hexadecimal number systems, two's complement for signed integers, floating-point representation, ASCII and Unicode for characters, bitmap and vector graphics, sampling and bit depth for sound), networking (LAN, WAN, the OSI model, protocols — TCP/IP, HTTP, FTP, DNS — and network security), and software (operating system functions, language translators — assembler, compiler, and interpreter — and system software). Component 2: Algorithms and Problem Solving (H046/02, 1 hour 30 minutes, 70 marks) is computational in character. It assesses algorithm design using pseudocode and flowcharts, data structures (arrays, stacks, queues, linked lists, and binary search trees), sorting algorithms (bubble sort, merge sort, insertion sort — and their time complexity using Big-O notation), searching algorithms (linear search and binary search), graph algorithms (Dijkstra's shortest path and depth-first and breadth-first traversal), programming concepts (variables, data types, selection, iteration, subroutines, and recursion), and computational thinking (decomposition, abstraction, pattern recognition, and algorithmic thinking). Students are expected to trace, write, and evaluate algorithms in OCR pseudocode notation.