Unit 1 Computer Science A-Level Ocr Questions And Answers 100% Verified A+ Guaranteed

register: Program counter= PC {Ans: holds the memory addresses of next instruction to be executed}what is opcode {Ans: specifies operation that is to be carried out}Describe computer before 1940s? {Ans: -calculate output using fixed instructions -perform only one set of instructions}where is harvard architrecture used {Ans: -used in specialised embedded systems and digital signal processing DSP, where speed takes priority and complexities of design}Buses in Von neumann architecture vs harvard {Ans: -Von neumann: One bus for data and instructions is a bottleneck (bottleneck = when these two meet then they become slow) One bus is simpler for control ​ unit design -harvard: Separate buses allow parallel access to data and instructions Control unit for two buses is more complicated and expensive}Pipe lining stages ? {Ans: 1. instruction enters pipeline 2. soon as one stage is completed then another instruction enters the pipeline 3. third instruction then enters before either of the other is completed}what are stored program concepts? {Ans: -program MUST be loaded into main memory to be executed by processor -instructions r fetched one at a time, decoded and executed SEQUENTIALLY -sequence of instructions can only be changed by a conditional or