OCR Computer Science A level paper 1 Test Guide With Complete Solution 2023

PC - Answer Program counter, contains the address of the next instruction CIR - Answer Current Instruction Register: stores the address of the next instruction currently being executed and decoded MAR - Answer Memory Address Register, holds relevant memory address (to read from or write to) MDR - Answer Memory Data Register, stores data being transferred to and from memory, acts as a buffer ALU - Answer Arithmetic and Logic Unit, does all mathematical calculations and makes all logical decisions Accumulator - Answer A storage register in the ALU that holds data temporarily while the data is processed and before it is transferred to memory. RISC - Answer Reduced Instruction Set Computer: Only simple instructions taking one clock cycle are executed - currently more widely used than CISC Advantages: allows for pipelining, execution will be quicker or as fast as CISC Disadvantages: Compiler has to do more work, more RAM required CISC - Answer Complex Instruction Set Computer: Large instruction set is used to minimise lines of code required - mainly used for microcontrollers and embedded systems Advantages: compiler has very little work to do, not much RAM required Disadvantages: Building in specialised instructions can be inefficient when only ~20% get used per program GPU - Answer Graphics Processing Unit - dedicated graphics processor on a graphics card, used to render images stored in the RAM of the graphics card. Multi-core CPU - Answer A CPU with more than one core on the same chip - makes use of parallel processing for optimum efficiency What affects processor performance? - Answer - The number of processor cores: more cores -> better performance - The processor's clock speed: faster clock speed -> better performance - Amount/type of cache memory: more/better cache memory -> better performance RAM - Answer Random Access Memory - stores programs and data currently in use. Volatile