1. Information and Communication Technology Fundamentals Credits Hours: 2+1 Instructor: Ayesha Bint Saleem

2. Computer Software

3. Presentation Credits Dr Altaf Khan, Virtual University Dr Junaid, EE Dept, SEECS “Introduction to Computers”, Peter Norton “Using Information Technology”, Williams & Sawyer

4. At the highest level, two things are required for computing Hardware: The physical equipment in a computing environment such as the computer and its peripheral devices (printers, speakers...) Software: The set of instructions that operates various parts of the hardware. Also termed as “computer program”

5. Computer Software The HW needs SW to be useful; the SW needs HW to be useful When the user needs something done by the computer, he/she gives instructions in the form of SW to computer HW These instructions need to be written in a language that is readily understood by computer uP (microprocessor)

6. Machine Language That language is called the machine language Machine language, though readily understood by microprocessors, is very difficult to write in for human programmers Language translators were invented to overcome this problem

7. Language Translators Human programmers write programs in a language that is easy to understand for them They use language translators to convert that program into machine language – a language that is easy to understand for the uPs

8. Two Major Types of SW System SW Programs that generally perform the background tasks in a computer. These programs, many times, talk directly to the HW Application SW Programs that generally interact with the user to perform work that is useful to the user. These programs generally talk to the HW through the assistance of system SW

9. Types of SW

10. Another way of classifying SW Shrink-Wrapped SW You can just go to a shop and buy it Custom-built SW You cannot just go to a shop and buy it; you have to find someone who can develop it for you

11. Who Owns Software? Generally, although a piece of SW that is being used by millions, it is not owned by any of them! Instead, it is owned by the maker of the SW The makers let us use their SW but keep the ownership to themselves. When we buy a SW package, we do not really buy it – we just buy a license that allows us to use it, the ownership stays with the maker However, there are variations on this theme …

12. 3 main types of SW licensees 1.Proprietary – Most software on a Windows PC or a Macintosh belongs to this category 2.Freeware – Most software on a Linux PC belongs to that category 3.Shareware – the category which lies between the above two categories

13. Proprietary SW License The user needs to pay the maker of the SW for buying a license that allows the user to use the SW The license, generally, does not transfer the ownership of the SW; it just allows the user to use it The user is legally barred from making copies of the licensed SW. Generally, the license is for the personal use only Most SW in use in the world is of this type Examples: Windows, Mac OS, MS Word, Adobe Photoshop, Norton Antivirus

14. Freeware SW License Also known as “Public Domain SW” Allows the user free use of the SW The author, however, generally retains ownership Can usually be downloaded from various Web sites Examples: Linux; LaTeX; Netscape Web browser – the Navigator; MS Web browser – the Internet Explorer

15. Freeware: Open-Source SW Some authors give away the machine code only, which is extremely difficult to modify, if at all! Others even give away the high-level language source code so that users can make changes according to their own requirements The later practice is called open-source licensing Examples: Linux; Netscape Navigator

16. Shareware SW License Allows the user free use of the SW, but with a request that the user pay the author a small amount (US$10-50) if the user is satisfied with the SW The author retains ownership Can usually be downloaded from various Web sites Examples: WinZip, Download Accelerator

17. Trialware Similar to shareware, but different The SW is usable for a short period only After an initial trial period that can range from a week to a few months, the SW self-destructs Can be downloaded from the Internet or alternatively, the user can receive a copy my snail-mail by writing to the maker of the SW Why trialware? So that the customer can have a risk-free trial for a limited-period only

18. Now to System Software…

19. Hardware Operating System Utility Language Translator Device Driver Scientific Apps. Business Apps. Productivity Apps. Entertainment Apps. System software Application software

20. System SW are programs that … Control the overall operation of the computer OS Interact directly with HW Device drivers Perform system management & maintenance Utilities Are used to develop or maintain other programs Language translators

21. The Booting Process Booting - the process of loading an operating system into a computer’s main memory

22. The Role of An OS User/ programmer convenience: simple, consistent way for applications to interact with the hardware. Greater resource utilization: manages the hardware and software resources of the computer system, often invisibly.

23. Benefit for application developers Don’t have to manage hardware complexity : Application developers can design software for an OS and it will run on all machines that support that OS. The OS hides and manages the hardware complexity and provide an Application Programmer Interface (API).

24. Kernel Command Interpreter (Shell) File Manager Device Manager GUI Loader OS Components

25. Kernel The heart of the OS Responsible for all the essential operations like managing resources, task scheduling, etc. Also contains low-level HW interfaces. Size important, as it is memory-resident

26. Core Tasks of an OS 1.Processor management 2.Memory management 3.Device management 4.File management 5.Application Interface 6.User Interface

27. Processor Management Various programs compete for the attention of the microprocessor. The OS plays the role of the honest referee, making sure that each application gets the necessary attention required for its proper execution. It tries to optimally manages the limited processing capacity of the microprocessor to the greatest good of all the users & apps

28. Memory Management Straight forward for a single-user, single tasking The OS ensures that: each application has enough private memory applications do not run into other application’s private memory. The OS is responsible for efficient utilization of hierarchical system memory (e.g. RAM, cache, etc.).

29. File Management A file system is a collection of directories, subdirectories, and files organized in a logical order The OS is responsible for maintaining the file system through indexing of filenames and their disk location. The OS can find any file in a logical and timely fashion

30. Device Management

31. Application Interface

32. User Interface Users communicate with the computer using a consistent user interface provided by the OS This UI can be a command-line interface in which a user types in the commands. Example: copy a:/file1.html c:/file1.html Or, it can be a graphical UI, where Windows, Icons, Menus, and a Pointing device (such as a mouse) is used to receive and display information. Example: With the help of the mouse, drag file1.html from drive a to drive c

33. Graphical User Interface

34. Command Line Interface

35. Types of Operating Systems Classification according to type of computers and applications they support 1.Real-Time Operating System (RTOS) 2.Single-User, Single Task 3.Single-User, Multi-Tasking 4.Multi-User, Multi-Tasking

36. RTOS (Real Time OS)

37. Single user/Single tasking OS OS designed to manage the computer so that one user can effectively do one thing at a time MS-DOS is an example single-tasking single- user OS with a command line interface Take up little space on disk Run on inexpensive computers

38. Single user/Multitasking OS Most popular OS, used by most of PCs and Laptops Lets a single user interact with several programs, simultaneously Mac OS, Linux Windows XP Require expensive computers Tend to be complex

39. Multi user/Multi tasking OS Many users connect to one computer Each user has a unique session UNIX, Linux, and VMS Maintenance can be easy Requires a powerful computer

40. Multi user/Multi tasking OS

41. Firmware OS components that are stored permanently on chip (ROM) and not on the disk drive When a computer is powered-on, firmware is the first program that it always executes Firmware consists of startup and a few low-level I/O routines that assist the computer in finding out and executing the rest of the OS On IBM-compatible PC’s, it is called BIOS

42. Utilities Computer programs that perform a particular function related to computer system management and maintenance Examples: 1. Anti-virus SW 2. Data compression SW 3.Disk optimization SW 4.Disk backup SW

43. Language Translators Programs that take code written in a HLL and translate it into a low-level language that is easily understood by the uP 1. Compiler translates the program written in a HLL in one go. The translated code is then used by the uP whenever the program needs to be run 2. Interpreter translates the HLL program one statement at time. It reads a single statement, translates it into machine language and passes that machine language code to the uP and then translates the next statement, and so on …

44. Device Drivers A computer program that facilitates the communication between the computer and a peripheral device (e.g. printer, mouse, etc.) It takes the instructions and/or data from the computer and converts them into a form that is readily understood by a peripheral device, and vice versa

45. Survey of common Operating Systems for

46. 7B-46 PC Operating Systems Microsoft Windows is the most popular Installed more than other OS combined Installed on about 95% of computers Apple and Linux represent the other 5%

47. 7B-47 PC Operating Systems DOS Disk Operating System Single user single-tasking OS Command line interface 16-bit OS Powerful Fast Supports legacy applications

48. DOS

49. 7B-49 DOS Application

53. 7B-53 PC Operating Systems Windows 9x 95, 98, and Millennium Edition (Me) 32-bit OS Supported 16-bit programs well Very pretty not stable OS Still found in large corporations 95 introduced the Start button 98 introduced active desktop Me improved multimedia software

55. 7B-55 PC Operating Systems Windows NT Designed for a powerful system 32-bit OS Very stable Windows NT Workstation Single user multi tasking OS Windows NT Server Multi user multi tasking OS Network operating system

56. WINDOWS 2000

57. 7B-57 PC Operating Systems Windows 2000 Look of 9x with NT stability Optimized for office and developers Application software ran very well Entertainment software ran very poorly

59. 7B-59 PC Operating Systems Windows XP Different look from 2000 Many different versions Digital multimedia support was enhanced Communications was enhanced Mobile computing became a priority

60. 7B-60 PC Operating Systems Windows Vista Microsoft’s newest desktop product Updated GUI Security was enhanced New multimedia creation tools included High system requirements

61. 7B-61 PC Operating Systems UNIX Runs on all computer types 32- or 64-bit Very stable and fast Command-line interface Can cost thousands of dollars

63. 7B-63 PC Operating Systems Linux Free or inexpensive version of UNIX 32-bit OS Very stable and fast Most flavors are open source X Windows GUI Command line interface is available

66. 7B-66 PC Operating Systems Macintosh operating systems OS X Based on FreeBSD Linux Very stable and easy to configure Only runs on Mac hardware

67. 7B-67 OS X Desktop

68. 7B-68 Network operating system Features Fast and stable Runs on servers Multi-user and multitasking OS 32- or 64-bit File and print sharing Data security

69. 7B-69 Networking Operating Systems NT Server Same core as NT Workstation Security added Multi user capability added RAID support included

70. 7B-70 Networking Operating Systems Windows 2000 Server Same technology as 2000 workstation Active Directory (AD) Central database of server resources Simplifies network management Distributed programs supported Server Standard Edition Advanced Server Edition Data Center Edition

71. 7B-71 Networking Operating Systems Windows 2003 Server Designed to compete with UNIX XP like interface Better support for XP computers MS.NET framework supported Distributed programs are supported Server Standard Edition Data Center Edition

72. 7B-72 Networking Operating Systems UNIX for servers Oldest NOS in widespread use Stable secure and fast Main OS for Internet and Web Large organizations depend on UNIX

73. 7B-73 Networking Operating Systems Linux for servers Popular in small businesses Stable, fast and inexpensive Linux’s popularity is growing

74. Embedded Operating Systems

75. 7B-75 Embedded Operating Systems Also called real time operating system Devices have EOS built in Designed to be very compact and efficient Run specialized application Stable and fast Deterministic interrupt latency Cell phones, PDAs, medical equipment

76. 7B-76 Embedded Operating Systems Windows XP embedded Based on Windows XP Customized for each device

77. 7B-77 Embedded Operating Systems Windows CE Not based on a desktop OS Customized for each device PDA and cell phones Microsoft Automotive will run in cars

80. Pocket PC OS Palm OS Symbian OS

81. 7B-81 Embedded Operating Systems Palm OS Standard on Palm PDA First PDA OS for consumers Can be found on cell phones

82. 7B-82 Embedded Operating Systems Pocket PC Developed to compete with Palm Not customizable Interacts securely with business networks Can control PCs through PC

83. 7B-83 Embedded Operating Systems Symbian Found in smart cell phones Games, Instant Messaging, Internet Full color display

84. OS Survey Summary

85. END of LECTURE