CGP OCR CS CPU and programming

Binary and Hexadecimal

• Binary Shifts

  • Used to multiply or divide by 2.

  • Left shifts multiply; right shifts divide.

  • Example: Shifting left doubles the number, while shifting right halves it.

• Hexadecimal (Hex)

  • Base-16 number system using digits 0-9 and letters A-F.

  • Shorter representation than binary.

  • Each hex character represents a 4-bit binary number (nibble).

  • Example: Hexadecimal 87 converts to denary 135.

• Binary Addition

  • Use column addition for binary numbers.

  • Carry over when necessary (e.g., 1 + 1 = 10).

• Overflow Errors

  • Occur when binary shifts exceed the bit limit.

  • Can lead to data loss or inaccuracies.

Boolean Logic

• Logic Gates

  • Basic gates: NOT, AND, OR.

  • Each gate has a specific function and truth table.

  • Logic gates can be combined for complex operations.

• Truth Tables

  • Show all possible input combinations and corresponding outputs.

  • Example: AND gate outputs 1 only if both inputs are 1.

• Complex Logic Circuits

  • Can involve multiple gates and inputs.

  • Written using logical statements.

Page 3: Network Topologies

• Client-Server Networks

  • Managed by a central server.

  • Clients send requests to the server for data.

  • Centralized storage for files and software.

• Star Topology

  • All devices connect to a central hub.

  • Easy to add devices; failure of one device does not affect others.

• Peer-to-Peer Networks

  • All devices are equal and connect directly.

  • Files are stored on individual devices.

• Mesh Topology

  • All devices connect to each other.

  • No single point of failure; data can reroute if one device fails.

Page 4: Network Security

• Data Protection Act

  • Governs the use of personal data.

  • Organizations must register and follow principles of data protection.

• Copyright, Designs and Patents Act

  • Protects intellectual property.

  • Illegal to share copyrighted material without permission.

• Computer Misuse Act

  • Prevents unauthorized access and modification of computer material.

Page 5: Computer Memory

• RAM (Random Access Memory)

  • Volatile memory used for active processes.

  • Speed affects overall system performance.

• CPU Performance

  • Depends on clock speed, number of cores, and cache size.

  • More cores allow for better multitasking.

• Virtual Memory

  • Secondary storage used as extra RAM when needed.

  • Slower than RAM, can affect performance.

Page 6: Computer Architecture

• Von Neumann Architecture

  • Describes how CPUs process data.

  • Involves fetching, decoding, and executing instructions.

• Registers in CPU

  • Include Program Counter (PC), Memory Address Register (MAR), and Accumulator.

  • Used to hold data and instructions during processing.

Page 7: Programming Basics

• Data Types

  • Main types: Integer, Real, Boolean, Character, String.

  • Each type has specific characteristics and memory requirements.

• Casting

  • Converting between data types using functions like int(), real(), bool(), and str().

• Arithmetic Operators

  • Basic operations: Addition, Subtraction, Multiplication, Division, Exponentiation.

  • Special operators: DIV (integer division) and MOD (remainder).

Page 8: Program Flow

• Control Structures

  • IF statements check conditions and execute code based on true/false outcomes.

  • SWITCH statements allow for multiple conditions.

• Flowcharts

  • Visual representation of algorithms.

  • Use different shapes for different commands (e.g., diamonds for decisions).

Page 9: Random Numbers

• Use in Programming

  • Generate unpredictable outcomes for games and simulations.

  • Functions like random(x, y) produce random integers or real numbers.

• Pseudo-Random Numbers

  • Generated by algorithms that appear random but follow a pattern.

Page 10: Constants and Variables

• Data Storage

  • Constants remain unchanged; variables can be modified.

  • Strings are sequences of characters, manipulated using various functions.

• String Manipulation

  • Common functions include length, upper, lower, substring, and concat.

Page 11: Algorithms

• Definition

  • A set of instructions for solving a problem.

  • Can be represented in pseudocode or flowcharts.

• Pseudocode

  • Structured like programming languages but more readable.

  • Allows for easy conversion to actual code.

• Flowcharts

  • Visual representation of algorithms, showing the flow of control.

Page 12: Network Security Threats

• Common Threats

  • Social engineering, phishing, SQL injections.

  • Importance of user education and strong passwords.

• Preventative Measures

  • Use of encryption, firewalls, and regular security testing.

Page 13: Summary

• Key Concepts

  • Understanding binary and hexadecimal systems.

  • Familiarity with Boolean logic and network topologies.

  • Knowledge of computer memory, architecture, and programming basics.

• Practical Applications

  • Apply knowledge in real-world scenarios, such as network setup and