2. Most modern operating systems incorporate these five components

3. User Interface (Shell) Provides a mechanism for the user and application programs to communicate with the operating system. – Types Of User Interfaces: Command – Executes single line commands Menu – Presents a list of single line commands GUI – Allows the user to issue commands by clicking on icons or selecting options from a menu Voice – User issues commands orally Web

4. 7 The User Interface

5. Fig. 7.1: People communicate with the operating system through the user interface or shell by issuing commands.

6. User Interface Functions Identify user Specify program to be executed Specify peripheral device requirements Support run-time intervention

7. Types of User Interfaces Command interface Menu interface Graphic user interface Expert system (voice-activated) interface Web-form interface

8. Types of User Interfaces Command Interface – Requires the user to type brief, cryptic commands. MS-DOS Line Commands. Application program function-key commands. – Require considerable user training. Menu Interface – Presents the user with a list of available options. – Easier to learn and easier to use. – Traversing multiple menus can be time-consuming.

9. Types of User Interfaces Graphic User Interface – Presents the user with a selection of windows, icons, menus, and pointers. Macintosh Microsoft Windows – Easy to understand, learn, and use – Consume considerable processor time and memory – Sometimes called an object-oriented interface or an icon-based interface.

10. Types of User Interfaces Expert System Interface – Voice-activated – Utilizes natural-language processing. Voice recognition Voice data entry – Requires a very powerful computer with a great deal of memory and a fast processor.

11. Types of User Interfaces Web-Form Interface – Follows the metaphor established by the Internet and the World Wide Web.

12. Summary

13. Most modern operating systems incorporate these five components

14. Device Management Responsible for controlling communications with the system’s peripheral devices. Interface Board Translates between internal and external form Channel Performs peripheral device-independent functions on large computers

15. Device Management Responsible for controlling communications with the system’s peripheral devices. Blocking Data Provides better utilization of disk/tape space

16. Most modern operating systems incorporate these five components

17. Processor Management Efficiently managing the processor’s time. Machine Cycle ICU ALU Object Code – Machine language version of the source program Concurrency – Multiple programs are loaded and executed concurrently Interrupt – An electronic signal that causes the system to save a link to the current program and start and operating system routine

18. Most modern operating systems incorporate these five components

19. File Management Incorporates routines that allow the user or programmer to create, delete, modify, and manipulate files by name. Logical Records Programmer’s view of I/O Physical Records Input – Transferring data into memory from a peripheral device Output – Transferring data from memory to a peripheral device Directory FAT - File Allocation Table VTOC – Volume Table of Contents

20. File Management Incorporates routines that allow the user or programmer to create, delete, modify, and manipulate files by name. Access Techniques Sequential – Accessing data in physical order Random – Accessing data without regard for physical order Data Base Centralized Programmer can ignore physical data structure

21. Most modern operating systems incorporate these five components

22. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Data is stored in memory in Binary form Absolute Address – A physical location in memory Relative Address An address relative to a base location Allows a routine to be loaded into a different location in memory

23. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Concurrency Multiple programs are loaded into memory and executed concurrently Cache Memory Object Code

24. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Resident Routines A routine that stays in memory Transient Routines A routine that is loaded into memory as needed Transient Area Memory for application programs and transient routines

25. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Fixed-Partition Management Divides the Transient Area into fixed-length partitions Dynamic Memory The Transient Area is treated as a pool of free space.

26. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Segmentation Programs are divided into independently addressed segments and stored in non- contiguous memory Paging Programs are divided into fixed-length pages and loaded into noncontiguous memory

27. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Overlay Structures Developed when the amount of available memory was limited Virtual Memory Real Memory External Paging Device Virtual Memory

28. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Virtual Storage Uses an external device as an extension of real memory Time Sharing Managing multiple concurrent users designed with interactive processing in mind

29. Memory Management Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other. Spooling Copying data from a slow input device to disk for subsequent processing