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Contents. What is an Operating System? Operating System Evaluation Operating System Design Some new components in the Operating Systems. What is a house?. People (service users). The house is a dwelling place which enables people to use various facilities in comfort

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  1. Contents • What is an Operating System? • Operating System Evaluation • Operating System Design • Some new components in the Operating Systems

  2. What is a house? People(service users) • The house is a dwelling place which enables people to use various facilities in comfort • A house gives consistent services and interfaces, e.g. switches, taps, sockets, aerial leads, doors, windows... House Hardware (e.g. power stations, satellites, water mains)

  3. What is an OS? Application Software • The OS is a software system which sits between the hardware and the application software • An OS give consistent services and interfaces, e.g. disc access, keyboard input, video output, memory management... Operating System Hardware

  4. Computing without an OS • It is possible to ignore the OS and take over the hardware directly • But software that does this is • making life difficult for itself • probably implementing its own internal OS anyway • usually a game system which does not need a complex, full-featured OS to work • Modern PC software uses the OS

  5. Computing with an OS Share the “processor power”… • Share Resources • E.g. Keep track of used and unused memory and drive space, arbitrate between demands on scarce resources • Multitasking • Run multiple programs in their own space, sharing resources • Networking • Communicate between computers even they have different hardware and software – standardised data formats • OS often comes with a GUI – may be many choices of GUI

  6. Examples • Big Computers • Bespoke versions of Linux e.g. CLE for HECToR (a UK National Supercomputing Service resource - http://www.hector.ac.uk/) • Servers • Windows Server, MacOS, Linux – many versions of each • Desk top computers • Windows (based on Windows NT) • MacOS (built on top of Unix) • Linux (many varieties, many GUIs) • Portable devices • Android (built on Linux), Windows Mobile 8, IOS (built on Unix), Blackberry (based on QNX)

  7. Operating System Evolution • The first computers had • small quantities of memory • limited processing abilities • a highly restrictive interface (keyboard only) • and monochrome displays

  8. Operating System Evolution • To control the hardware and perform useful tasks, simple instructions had to be given • These instructions took the form of typed sequences of commands • This was the birth of the command-line interface (the CLI) • An early but powerful version was UNIX (also available in a slightly different form as Linux for modern PCs)

  9. Loading the OS - BIOS v UEFI • EFI (now UEFI) is a secure boot loader system that replaces the old BIOS approach • Checks the NVRAM custom settings • Loads only the signed interrupt handlers and device drivers • Initializes registers and power management • Performs the power-on self-test (POST) • Displays system settings • Determines which devices are bootable • Initiates the signed OS start-up sequence

  10. Operating System Evolution - GUIs • Most people are used to using a GUI (Graphical User Interface) to control a computer • The GUI was invented in the early 1970’s at Xerox PARC (Palo Alto Research Center) • Modern GUIs are derived from this first GUI A screen grab from Windows 3.1

  11. Operating System Design • The design of the operating system may be very closely tied to the hardware platform that it is to be run on • Example: Older Blackberry & Nokia phone software • It is possible to have a “hardware abstraction layer” to reduce the hardware-specific nature of an OS • Example: Device drivers for Windows • Look up “monolithic” and “micro-kernel” OSes

  12. Desktop Windows Manager • Their drawing is redirected to off-screen surfaces in video memory, which are then rendered into a desktop image and presented on the display • The contents of every open window is stored in video memory to facilitate movement of windows.

  13. Wide range of systems - Example • There are 20 million cars on the road running QNX in various forms – for their real-time engine monitoring to their built in entertainment systems. • Cars use technologies including entertainment and real-time monitoring, but are moving towards self-driving technology, parking guidance and networked entertainment and information systems • All of this predicates a powerful OS • Key players are Microsoft (Windows Embedded Automotive), Google (Android), Tizen [Samsung and Intel] (Linux), Audi (MMI) • See: http://www.forbes.com/sites/parmyolson/2013/01/03/among-the-hot-trends-for-ces-2013-cars-that-run-on-android/

  14. Conclusion • The “real-time OS” for “embedded systems” is an area of much development at the moment • Example: the old Sega Dreamcast games console ran Windows CE OS (an early version of the MS Windows Mobile OS) • Smart cards, engine management systems, mobile phones, Internet devices all run some kind of OS • Wherever there is a CPU there is likely to be an OS of some type

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