1.2.1 systems software

• Manage hardware/peripherals (track all devices connected to system, device drivers) • file management (storing files in secondary storage, searching for / copying / moving / renaming files + folders) • Provide a user interface (allows user to interact with software/hardware) • manages system security / user management (controlling who can access system / manage user profiles. controlling who can access certain resources on system / manage access rights) • provides a platform for utilities (used to monitor / manage / maintain computer. to manage security) • provide a platform on which to run the software (allows additional software to be installed, allows user to complete additional tasks - platform for networking and multitasking) • resource/memory management (paging, segmentation. moving data between RAM and secondary storage/VM, allocating and deallocating memory) • manages external devices (efficient comms with devices and manage functionality issues) • managing the processor/scheduling • handle interrupts

• User interface • Memory/resource Management • Interrupt handling • Processor scheduling

Windows, Android, Linux, iOS

• the core of the operating system that provides basic services for all other parts of the OS.

• Loading and unloading programs from RAM • CPU scheduling • Memory management • Storing files to and from storage • File management • Data security

Because different devices have different priorities. e.g. A kernel for a mobile phone will need to be as power efficient as possible whereas one for a desktop will be optimised for performance

• software installed which enables communication between OS and device so OS can interact with and control it. (comms between hardware and software) • Mr Caselton can drive but can’t use all bus functionality. Bus driver (software) has more capability.

• Translates commands from the OS into series of hardware specific commands that only that device understands. The device can also pass data back to the OS using the device driver.

hardware dependent and OS specific

The company who created the device.

• Software that allows the user to interact with computer’s hardware. • WIMP (Windows, Icons, Menus, Pointers)

GUI and CLI

• graphical user interface • uses WIMP (Windows, Icons, Menus, Pointers) to provide clear graphical interface for user to control computer. • visual, interactive and optimised for mouse and touch gesture input • allows for multitasking • can take longer to perform tasks • more resource intensive • requires more power (more data involved)

• command line interface • allows user to type commands directly into the computer. • more reliable + more control due to direct communication from commands • requires less power • hard to use without knowledge of commands. But if experienced, its fast to use

• Print queue • File management • Encryption software • Compression Software • Antivirus • Disk defragmenter

• Allocating memory to each program that runs • Mapping logical addresses to actual physical addresses • Prevents programs from overwriting each other • Moving files to virtual memory when running short on RAM

Paging (Pagination) and Segmentation

• both allow programs to run despite insufficient memory • pages and segments are stored on disk • pages and segments are transferred into memory when needed • Allows programs to be stored in memory non-contiguously • both are ways of partitioning memory

• pages = fixed size, segments = different sizes • pages made to fit section of memory, segments are complete sections of program • pages are physical divisions but segments are logical divisions

• An application running is split into processes (segments) • Each segment is a complete section of program that is allocated a space in RAM and executed separately. • The large program is run by running the smaller segments as required.

• Allows a program to be run on a system without using up too much memory.

• logical divisions of varied sizes

A segment which holds the executable instructions for the process.

A segment which holds all of the variables for the process.