Systems Software

1. Systems Software

2. Systems Software • Software needed to manage systems hardware resources • Operating System (OS) is a set of programs that control and manage computer system resources • Common functions include: • Control system hardware • Coordinate program execution • Provide connection services to devices and network • Administer access to system resources • Computer startup and shutdown • User interface • System Utilities provide additional functionality required for, or to enhance, systems operations and management

3. Operating system

4. Operating System Categories • Operating systems are designed to support: • A single users - standalone • Multiple users – server • Dedicated to a single device - embedded • Many of the functions are common, differences include: • Application idiosyncrasies • System access administration • Resource management • Task or job management • Operating systems require administration • Adding or removing users and they access rights • Adding or removing resources (e.g. memory, devices) • Applying updates • Tuning resources More skill and effort is needed to administer servers than standalone systems

5. Single User Operating Systems • A single user operating system is one that works on a desktop computer, notebook computer, or mobile computing device, supporting a single concurrent user • Examples of standalone operating systems are: • Windows, Windows Mobile • Apple OS • Unix / Linux • Android • iOS (iPhone, iPad) • A server (multi-user) operating systemis designed to support multiple concurrent operations on behalf of client systems • Examples of Server operating systems are: • Windows • Apple • Unix / Linux • Solaris (Sun Microsystems)

6. Embedded Operating Systems • An embedded operating system resides on a Flash ROM chip on a mobile device, consumer electronic device, etc. • Examples include: • Apple iOS • Android • Symbian OS • Palm OS • Windows Mobile and CE • Blackberry • EOS – Canon camera OS

7. Operating System Startup

8. Operating System Concurrency • Operating systems concepts • Single versus multi-user • Task or Process versus Application • Single versus multi-tasking • Foreground versus Background tasks, examples: • Printing • Virus Scans • Priorities • Multi-tasking versus Multiprocessing • Multiprocessing requires system hardware to have multiple processors (or cores) 1 per concurrent process

9. Operating System User Interface • A user interface controls how you enter data and instructions and how information is displayed on the screen • The OS often provides for more than one user interface • With a graphical user interface (GUI), you interact with menus and visual images to invoke the needed commands • With a command-line interface, a user directly enters commands E.g. DOS prompt • Certain activities may only provide a command line interface

10. Operating System Memory Management Programs can only be executed and data manipulated when they are in RAM Memory management optimizes the use of RAM Virtual memory is a portion of a storage medium functioning as additional RAM Program instructions and data are shuttle between Real and Virtual memory Performance problems can result of insufficient real memory

11. Operating System Virtualization VM 1 VM 2 VM 3 VM n … Virtual Operating System Server Virtualization • Creating multiple apparent instances of servers on one physical server (hardware) • Supports different operating systems (e.g. Windows and Linux on same hardware) • Allows for the sharing of hardware resources • Practical because most servers resources are not fully utilized by any single application or server instance

12. Operating System Device Drivers Device Drivers • A program that defines the system interface for a specific device or device type (e.g. mouse, keyboard, printer) • Allows the operating system and other programs to access devices • Plug-and-Play allows for the OS to find and configure a new device driver for a detected device without a user’s intervention

13. Operating System Network Connectivity • Operating systems provide a means to establish connections: • Local • Wide Area, including the Internet • Dependent on systems network hardware capabilities

14. Operating System User Administration • Each user on a systems has a user account which includes: • A user name, or user ID, identifies a specific user • A password is a private combination of characters associated with the user name • Access rights to resources and data • Potentially user related logs • One or more users have Administrator rights which allow them to manage access and perform other systems tasks (e.g. installing applications)

15. Utility Programs

16. Utility Programs • A utility program is system software that performs • Systems management and maintenance tasks • Miscellaneous /accessory functions • Some utilities are bundled/accompany the operating system, others are sold as add-on products.

17. Performance Monitoring A program that assesses and reports utilization of various computer resources and devices to identify and help resolve issues. Resources monitored include: CPU, Memory, IO interfaces, Running tasks Limited functionality provided within the OS, other require separate software and potentially hardware (e.g. probes)

18. Disk Management • File manager • Displaying a list of files • Organizing files in folders • Copying, renaming, deleting, moving, and sorting files and folders • Creating shortcuts • Search utility • Desktop search (all documents, …) • Extended search (emails, web contents, …) • Desktop search tool providers include Microsoft, Google, … They want your eyeballs • Disk cleanuputility • Old downloads • Temporary Internet files • Deleted files • Unused program files

19. Disk Management A disk defragmenter reorganizes the files and unused space on a computer’s hard disk so that the operating system accesses data more quickly and programs run faster Disk space becomes fragmented as files are added and then deleted. A fragmented disk performs slower because single files are no longer stored sequentially on the disk. Defragmenting reallocates files

20. Disk Management, cont’d. • File compression utility shrinks the size of a file(s) • Compressing files frees up room on the storage media • Standard compression works at the bit level looking for like patterns (redundant) that can be removed by replacing with a repetition indicator • Two types of compression • Lossless • Some loss (e.g. fidelity of a picture) • Deduplication is another form of compression • Removes redundant files or other objects

21. Disk Management, cont’d • Backup/Restore utility • Copy a disk image or selected files to an alternate media • Copy may be sent offsite or to an alternate site in the event of a disaster at the primary site • Restore a disk image or selected files • To recover from lost or corrupted data • To recover from a disk hardware failure • Archive utility • A copy of selected files is made on a like or lower cost media (e.g. slower disk, tape) • Copy is retained for a specific period set in a retention schedule and then automatically purged

22. System Security • Systems Administration Tools • Described earlier • Firewall • Detects and prevents a computer from unauthorized intrusions • Filters • Programs that remove or block certain items from being displayed, received or sent, such as: • Email (objectionable content, viruses, SPAM, phishing • Pop-up and pop-under blockers • Web filtering • In-bound traffic most common • Outbound traffic to protect company assets • System logsmaintain record of system access, error conditions, etc.