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A-Level Computer Science Paper 1 Overview

Jun 1, 2025

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A-Level Complete Paper 1 Revision

Introduction

  • Greetings and purpose of the lecture.
  • Focus on revising key computer science topics for A-Level Paper 1.

1.1.1 Structure and Function of the Processor

Control Unit (CU)

  • Sends out control signals to parts of the CPU.
  • Executes programs via the Fetch-Decode-Execute cycle.
  • Contains the clock and decoder.

Arithmetic Logic Unit (ALU)

  • Performs calculations and logical operations.
  • Handles comparisons and basic arithmetic operations.

Registers

  • Program Counter (PC): Holds address of the next instruction.
  • Memory Address Register (MAR): Stores address of data for memory operations.
  • Memory Data Register (MDR): Stores data being transferred to/from memory.
  • Current Instruction Register (CIR): Holds the instruction being decoded/executed.
  • Accumulator (ACC): Stores results of ALU operations.

Buses

  • Address Bus: Carries memory address.
  • Data Bus: Transfers data between CPU and memory/IO devices.
  • Control Bus: Sends control signals.

Fetch-Decode-Execute Cycle

  • Fetch: Steps to retrieve instruction from memory.
  • Decode: Control Unit decodes the instruction.
  • Execute: Instruction is executed by the CPU.

Factors Affecting CPU Performance

  • Clock Speed: Controls speed of FDE cycle.
  • Overclocking: Increases performance but risks damage.
  • Cache: Fast memory for frequently used data.
  • Number of Cores: Multi-processing capabilities.
  • Use of Pipelining: Parallel processing by fetching while decoding/executing.

Processor Architectures

  • Von Neumann: Single control unit and ALU, stores data and instructions together.
  • Harvard: Separate memory for instructions and data.
  • Contemporary: Uses parallel processing techniques like SIMD and MIMD.

Types of Processors

  • CISC (Complex Instruction Set Computing): More instructions, more power.
  • RISC (Reduced Instruction Set Computing): Fewer instructions, efficient pipelining.
  • GPUs: Specialized for graphical calculations, also used in other fields.

1.1.3 Input, Output, and Storage

Input and Output Devices

  • Input: Keyboard, mouse, microphone, etc.
  • Output: Printer, speakers, monitors, etc.

Storage Devices

  • Categories: Magnetic, Flash, Optical.
  • Considerations: Cost, speed, capacity, durability, reliability.

RAM and ROM

  • RAM: Temporary storage for running programs and data.
  • ROM: Non-volatile storage, often used for BIOS.

Virtual Storage

  • Cloud storage, accessible from anywhere with internet.
  • Advantages and disadvantages considered.

1.2.1 System Software

Operating System Functions

  • Manages hardware, provides UI, manages security, etc.

Memory Management and Interrupts

  • Allocation of RAM and handling of interrupts for efficient CPU usage.

Scheduling Algorithms

  • Different algorithms for managing CPU time (e.g., Round Robin, First Come First Served).

Types of Operating Systems

  • Multitasking, Multi-user, Distributed, Embedded, Real-time.

Device Drivers and BIOS

  • Role of device drivers and BIOS in system operation.

Virtual Machines

  • Simulate a computer system, used for running multiple OS on one hardware.

1.2.2 Applications Generation

Application and Utility Software

  • Application software: Specific tasks (e.g., word processor).
  • Utilities: System maintenance (e.g., disk cleanup).

Open Source vs. Closed Source

  • Open Source: Source code available.
  • Closed Source: Proprietary software.

Translators

  • Assemblers, Interpreters, Compilers: Convert source code to machine code.

Compilation Process

  • Steps: Lexical Analysis, Syntax Analysis, Code Generation.

1.2.3 Software Development

Software Development Life Cycle

  • Models: Waterfall, RAD, Spiral, Agile.

Algorithmic Thinking

  • Using algorithms to solve problems.

1.2.4 Types of Programming Language

Paradigms

  • Low-level and high-level languages.
  • Imperative (Procedural and Object-Oriented) and Declarative languages.

Assembly Language

  • Basics of programming in Assembly.

Object-Oriented Concepts

  • Class, Object, Abstraction, Encapsulation, Inheritance, Polymorphism.

1.3.1 Compression, Encryption, and Hashing

Compression

  • Lossy vs. Lossless.

Encryption

  • Symmetric vs. Asymmetric.

Hashing

  • Use cases and potential issues.

1.3.2 Databases

Database Concepts

  • Flat file vs. Relational databases.

SQL

  • Using SQL for data manipulation and retrieval.

Normalization

  • Process of organizing data into tables.

1.3.3 Networks

Network Concepts

  • LAN, WAN, PAN.

Network Protocols

  • TCP/IP, HTTP, FTP, SMTP, etc.

Network Security

  • Firewalls, Encryption, VPNs, etc.

1.3.4 Web Technologies

Web Development

  • HTML, CSS, JavaScript.

Search Engines

  • How they index and rank websites.

Client-Side vs. Server-Side Scripting

  • Differences and use cases.

1.4.1 Data Types

Primitive Data Types

  • Character, String, Boolean, Integer, Real.

Binary Representation

  • Conversions between binary, decimal, hexadecimal.

1.4.2 Data Structures

Arrays, Records, Lists, Tuples

  • Various data structures and their uses.

Linked Lists, Stacks, Queues

  • Implementation and operations.

Trees and Graphs

  • Traversal methods and uses.

Hash Tables

  • Managing data with hashing.

1.4.3 Boolean Algebra

Logic Gates and Circuits

  • AND, OR, NOT, XOR gates.

Boolean Laws and Rules

  • Simplification techniques.

1.5.1 Computing Related Legislation

Key Acts

  • Computer Misuse Act, Data Protection Act, Copyright Design and Patent Act.

1.5.2 Moral and Ethical Issues

Topics

  • AI, Environmental issues, Censorship, Monitoring, etc.

These notes provide a comprehensive overview of the key topics covered in the lecture, suitable for A-Level Computer Science Paper 1 revision.

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