Computer Science Revision Paper 1

Computer Science Revision Paper 1

1. Computer Legislation

   • Data Protection Act 2018
     • This act gives rights to data subjects to access the data stored about them.
     • The Six Principles
       • Data should be kept safe and secure.
       • Data must only be used in a fair, lawful and transparent way.
       • Data must only be used for the specified purpose.
       • Data should be adequate, relevant and not excessive for the specified use.
       • Data must be accurate and kept up to date.
       • Data should not be kept for longer than is necessary.
     • Before collecting personal data, the organisation must register with the government saying what data they'll collect and how they'll use it.
     • Subjects have the right to see, amend and delete the data.
     • Organizations don't have to disclose data that could affect national security or the outcome of a court case.
   • The Copyright, Designs and Patents Act 1988
     • Protects intellectual security that people have created.
       • Covers written or recorded content
     • What is Illegal
       • Sharing copyrighted files without permission
       • Using unlicensed software
       • Plagiarise someone's work
   • The computer misuse act 1990
     • Was introduced to help stop hacking and cyber crime.
     • Three New Offences
       • Gaining unauthorised access to a private network or device through hacking or other means (like social engineering)
       • Gaining unauthorised access to a private network or device in order to commit a crime
       • Unauthorised modification of computer material.

2. Network Protocols

   • Standards
     • A standard is a set of agreed upon requirements for hardware and software.
     • Standards are important so that products mad are compatible with eachother.
   • MAC Addresses
     • Unique identifier used for communication on the same network.
     • Assigned to all network enabled devices by the manufacturer.
     • They are 48 or 64 bit strings of binary numbers. They are usually converted to hex to make them easier.
     • Mainly used by the ethernet protocol on LANs. Switches use them to direct data to the right device.
   • IP Addresses
     • Used when sending data between IP/TCP networks (the internet)
     • Are assigned manually or automatically before accessing the network.
     • IPV4 - 32 bit
     • IPV6 - 128 bit
   • Definitions
     • IP
       • Network Layer
     • TCP
       • Transport Layer

3. Von Neumann

   • The CPU has three main parts
     • The Control Unit (CU)
       • Has overall control of the CPU.
       • Processes all the data and instructions.
       • Controls the flow of data inside and out of the CPU.
     • The Arithmetic Logic Unit (ALU)
       • Completes simple addition and subtraction and compares sizes of numbers.
       • Performs logic operations such as AND, OR, NOT as well as binary shifts.
       • Has the accumulator register.
     • The Cache
       • Very fast memory in the CPU. Slower than registers but faster than RAM.
       • Stores regularly used data so the CPU can access it quickly.
       • Low capacity and relatively expensive.
       • Levels Of Cache
         • L1
           • Quickest
           • Least memory
         • L2
           • Middle ground
         • L3
           • Slowest
           • Most memory
   • Registers
     • They hold tiny amounts of data but are very fast to read and write to.
     • Different registers
       • Program Counter (PC)
         • Holds the memory address of the next instruction or data to be fetched from memory.
       • Memory Address Register (MAR)
         • Holds the current memory address of the data or instruction being processed.
       • Memory Data Register (MDR)
         • Holds the actual data or instruction.
       • Accumulator
         • Stores all the intermitent results of calculations in the ALU.

4. Hardware Required in Networks

   • Network Interface Card (NIC)
     • The piece of hardware that allows a device to connect to a network
   • Switch
     • Connects devices in a LAN and directs data to it's intended location.
   • Router
     • Responsible for transmitting between networks. Direct packets to their destination.