The OS

The OS

1. Types of OS

   • Real-time
     • Handles input within a guarenteed latency
     • Can set priority to incoming data - called priority interrupts
   • Single user
     • Only has one user connected at any time
     • Can be either single or multi tasking
   • Multi user
     • Can have multiple users connected simulatneously
     • Multi-tasking

2. Functions of the OS

   • Access to hardware
     • Device drivers
     • Machine code that allows a device to talk to the rest of the system
     • When a peripheral is required an interrupt is generated to signal to the OS that it neds to deal with something
   • Access to software
   • Security features
     • Login credentials
     • WiFi password
     • Shared resource access management
     • Access to network areas
   • Provide user interface
     • Graphical User Interface (GUI)
       • Windows, Icons, Menus, Pointer
     • Command Line Interface (CLI)
       • Navigate using commands in a terminal
     • Menu Based Interface
       • Navigate using a series of menus

3. Role of the Kernel

   • Memory management
     • Responsible for allocating memory to open tasks
     • Ensures system has enough memory for each task
     • Active programs have priority over background task
   • Program execution
     • Makes sure system is ready to execute programs
     • Translates code to the appropriate system
   • Disk access
     • Ensures that required data is queued or given priority from backing storage
     • Controls which programs users can read/write to the disk & what data they have access to
   • File management
     • Ensures data is stored in a format that the system can understand such as NTFS and FAT-32
     • In charge of journalling (keeping logs of changes) and indexing (identifying where data is stored)
   • Multi tasking
     • Controls time-slicing
     • Where a program is sliced into smaller tasks and allocated them to be executed
   • Mode switching
     • Allows user to switch from low-level to high-level