AN Reviewer

• Program – a set of instructions that tells the computer what to do.
• Software – a set of interrelated programs.
• Types of Software

  1. System software
  2. Application software
• Type of Software

  System software – used to manipulate the basic operations of a computer system.
• Type of Software

  Application software – used to accomplish specialized tasks for computer users.
• Types of application software

  Document production software – used to compose, edit, print, and electronically published documents.
• Types of application software

  Spreadsheet software – used to create and manipulate spreadsheets electronically for analysis, planning, and modeling.
• Types of application software

  Presentation software – used to create and display information in the form of slide shows.
• Types of application software

  Database management software – used to store, modify, and retrieve information from a database in an organized and structured manner.
• Types of application software

  Business software – can provide users with tools for business management
• Types of application software

  Multimedia software – can manipulate pictures, sound, and video.
• Types of application software

  Entertainment software - an refer to video games, screen savers, programs to display motion pictures or play recorded music, and other forms of entertainment which can be experienced through use of a computing device.
• System programming – the act of developing system software.
• Types of programming languages

  Machine language – the natural or primitive language that the computer actually understands.
• Types of programming languages

  Low-level language/assembly language – uses abbreviations or mnemonics in place of binary patterns.
• Types of programming languages

  High-level language – uses English-like commands.
• Types of system programs

  Operating Systems – set of programs that are required for providing interface between the different applications and hardware of the computer systems or mobile phones.
• Types of system programs

  Language translators – convert a high-level language program/assembly language program into machine language.
• Types of system programs

  Linker – a system that combines or links the modules together with the libraries which then form a single executable program called load module.
• Types of system programs

  Loader – responsible for bringing the load module to the main memory for execution.
• Address binding – the process of assigning or mapping symbolic references to actual memory locations.
• Physical address/absolute address – the actual main memory location.
• Techniques in placing the load module in the main memory

  Absolute loading – the load module has actual memory addresses assigned instead of symbolic variables.
• Techniques in placing the load module in the main memory

  Relocatable loading – address binding is performed right before the load module is loaded and the address assignment was based on the available main memory location at that time.
• Techniques in placing the load module in the main memory

  Dynamic run-time loading – the absolute address is not generated when loaded, but only when it is needed by the CPU.
• Operating System – a system software that allows users or the application programs they are using to interact with the computer hardware in an easy and convenient manner.
• Major functions of an OS

  It creates a virtual machine interface between the user/application program and the hardware.
• Major functions of an OS

  It acts as the computer’s resource manager or resource allocator.
• Important resources managed by the OS

  1. CPU
  2. Main memory
  3. I/O devices
• Major functions of an OS

  It functions as the program launcher.
• Main goals of the OS

  It should make the computer easy and convenient to use.
• Main goals of the OS

  It should manage the resources of the computer system to make them more efficient.
• Main goals of the OS

  It should execute and control programs.
• Bootstrap program – stored in the computer’s Read-Only Memory (ROM) and is executed upon power on.
• Boot Block Loader – locates the OS and loads it in the main memory.
• Two parts of OS

  Kernel – the heart and soul of the OS; directly controls the computer system hardware and performs the services of the OS.
• Two parts of OS

  Shell (Command Interpreter) – part of the OS that serves as the interface between users and the kernel.
• Types of shell

  Command-Line Interface (CLI) – requires users to type the commands at a prompt; requires knowledge of commands and proper instruction formulation.
• Types of shell

  Graphical User Interface (GUI) – requires users to enter commands by either using drop-down menus or by clicking on icons using a mouse pointer.
• Services provided by the OS

  Program execution. The OS locates a program in the secondary storage, loads it in the memory and executes it.