Higher Computing Science

Higher Computing Science

1. Languages and environments

   • Low-Level
     • Corresponds directly to a processor's instruction set
   • High-Level
     • Written in English
   • Procedural
     • Uses procedures, functions or sub-routines.
     • Visual Basic
   • Declarative
     • Uses facts, rules and queries to interrogate the knowledge base
     • {"item": "bread", "type": "wheat"}
   • Object-Orientated
     • Uses classes

2. Parameters

   • • Formal - this refers to the variable name used within the subroutine to hold the data passed into it, for example, age.
     • Actual - this refers to the actual data that is passed into the subroutine, for example, 45.
   • • Global - these variables can be used throughout a program at any point in the code
     • Local - the values stored in these variables exist within only one part of the code, usually within a subroutine

3. Methods of Testing

   • Dry Run - reading the code and predicting what will happen without actually running the code.
   • Trace Table - lists the variables in a program and tracks the values they store as the code is executed store as the code is executed.
   • Test Plan
     • Normal, Extreme, Exceptional
   • Beta Testing - final stage of testing involving community

4. Software Development Methodologies

   • Rapid Application Development
     • Involves building prototypes of parts of the software
       • Easier to test
       • Feedback early on
   • Agile Methodologies
     • Lack of emphasis on design and documentation

5. Legal Implications

   • Computer Misuse Act
     • Unauthorised access of a computer
     • Unauthorised access of a computer to commit further criminal offences
     • Unauthorised altering of computer data
   • Copyright, Designs and Patents Act
     • Protect time, money and effort invested by content creators.
   • The Communications ACt
     • Use other people's Wi-Fi broadband connections without permission
     • Offensive / upsetting messaging
     • Unauthorised interception of communications (e.g. phone hacking)
   • Regulation of Investigatory Powers Act (RIPA)
     • Certain organisations can intercept data, access password protected data and carry out surveillance for the purposes of crime prevention.
     • Protects individuals' rights to privacy
     • The employers must notify employees if they want to intercept communications data

6. Processor Buses

   • Data Bus
     • Transfer data between main memory and the processor.
     • Two-way
   • Address Bus
     • Specify the address of the memory location
     • One-way
   • Control Bus
     • Read - Reads the contents of a memory location
     • Write - Writes an item of data from the processor into a memory location
     • Clock - sends a regular series of pulses into the processor to synchronise events.
     • Reset - stop execution of current program and then to reboot
     • Interrupt - peripheral devices, such as printers, can send a signal on the interrupt line into the processor when the require attention. This causes the processor to deal with the interrupting device.