Designing software

• Information systems


  Comprise people, data, processes and digital systems
• Digital systems


  • Networks
  • Protocols
  • Application architecture patterns
  • Software
  • Hardware
• Hardware


  Requires software instructions to control it
• Software


  Requires hardware to carry out instructions
• Hardware


  • Input devices
  • Output devices
  • Processing hardware
  • Storage hardware
  • Communication hardware
• Central processing unit (CPU)


  The core processing hardware of a computer system
• Reduced instruction set computing (RISC) CPUs


  • Have smaller instruction sets than complex instruction set computing (CISC) CPUs
• Graphics processor units (GPUs)


  Very fast processors designed for high-speed image processing in graphics cards
• Storage hardware


  • Primary storage
  • Secondary storage
• Primary storage


  A computer's random-access memory (RAM)
• Secondary storage


  • Hard disk drives (HDDs)
  • Solid state drives (SSDs)
  • Network-attached storage devices (NASs)
• HDDs


  • Cheap and reliable long-term storage medium with large capacity
• SSDs


  • Fast and efficient storage medium that is more expensive than HDDs
• NAS devices


  • Networked sets of HDDs or SSDs that provide for faster speed, higher capacity and data protection via redundancy
• Communication


  Used for sending and receiving data and information
• Ports


  Physical sockets or connectors that carry data between a computer and external devices such as peripherals
• Software drivers


  Computer programs that control internal and external computer devices
• Software


  Controls computing devices to process data
• System software tools


  • Used by a computer to manage hardware and run programs
• Applications


  Used to perform work or complete larger tasks
• Utilities


  Single-purpose software tools that complete specific jobs or add functionality to an operating system
• Operating system


  System software that controls a computer's hardware and runs application software
• Programming languages


  Used to give instructions to computer processors
• High-level programming languages


  • Computer-independent and use natural language elements
• Low-level programming languages


  • Reliant on the architecture of a particular computer and have comments tightly linked to processor instructions
• Source code editors


  Come with specialist features such as syntax highlighting, code completion and line numbering
• Compilers


  Convert source code into executable programs
• Interpreters


  Directly execute source code at run-time without needing pre-compilation
• Code that has been compiled for one platform will not work on another platform unless it has been re-compiled for that platform
• Integrated Development Environment (IDE)

  Used by programmers as it provides tools to aid in programming
• Storage structure


  A location in RAM where data is stored during the execution of a program
• Data storage structures


  • Variables
  • Constants
• Variables


  Store values that can be changed by a program
• Constants


  Store values that are fixed and unchanging during a program's execution
• Project plan


  Helps track and monitor the progress of a project
• Tasks


  Activities within a project that take time and resources
• Task dependencies


  • One task cannot begin until one or more other tasks have been completed
• Milestone


  A task that takes no actual time but is a significant event within the project timeline
• Scope of a solution


  Outlines its boundaries or parameters
• Scope creep


  When a client changes the scope of a project during its life cycle