Computer Software Chapter 3 of book... Computer Software ● Software consists of electronic instructions to tell computer how to perform desired task – Software can come on a CD, disk, or off the internet, among other forms ● Software can be classified as either system software or application software Application Software ● Software that user typically interacts with – Developed to perform a particular task for users (rather than the computer itself) – Includes Word Processing, spreadsheets, games – Examples are Microsoft Word and World of Warcraft System Software ● Allows application software to interact with computer and perform desired task for user ● Helps computer manage resources ● Basic components of system software – Operating systems – Device Drivers – Utility Programs Operating System ● Principle component of system software in computing system ● Every general-purpose computer must have operating system in order to run other programs ● Allows user to focus on own tasks rather than managing computer ● Popular operating systems include Windows, Linux, Macintosh OS Operating System ● Kernel/supervisor – central component of most operating systems – Provides communication between hardware and software components of computer – Kernel provides “abstraction layer” for the computer hardware (CPU, memory, devices) ● Application software can be written without knowing the details of the particular CPU/memory/devices, only needs to know how to interact with the kernel – Without a kernel, application software would be significantly more difficult to design Operating System ● Operating system tasks include – Booting ● Process of loading the operating system into a computer's main memory – CPU Management ● Performed by kernel that remains in memory – File Management ● Operating system must know location of saved files – Task Management ● Computer may need to perform word processing and play music at the same time – Security Management ● Password options for system/file access Operating Systems ● Multiple options ● Platform – processor model and operating system where computer system based – Examples are “Mac Platform”, “Windows Platform”, “PC Platform”, as well as Solaris and others Operating Systems ● Legacy systems – Older, may be outdated, but still functional – Still used rather than upgrading for some reason ● System works, so no reason for changing ● Maybe more expensive to upgrade rather than maintain current system ● System must always be available, complicates upgrading ● Way system works not understood (designers may have left company) – The DOS operating system is an important legacy system The DOS operating system ● DOS stands for Disk Operating System – Initially released as PC-DOS in 1982 – Licensed by Microsoft to other computer makers as MS- DOS – Original operating produced by Microsoft – Used a command-driver interface rather than a graphical user interface – Earlier versions of Windows built on top of DOS – Main uses of DOS today are running classic DOS games, running business software that only supports DOS, and supporting embedded DOS systems such as a computerized cash register The DOS operating system Startup sequence of FreeDOS Describes itself as a “free DOS-compatible operating system for IBM- PC compatible systems” Macintosh Operating System ● Launched in 1984 – Super Bowl commercial introduced the Macintosh; ad introduced by Steve Jobs in flip: http://www.youtube.com/watch?v=lSiQA6KKyJo – Introductions to the Mac by Steve Jobs: http://www.youtube.com/watch?v=G0FtgZNOD44 ● Used a graphical user interface (GUI) – Interface based on work done at Xerox, which based work on research at Stanford Research Institute – Eventually inspired Microsoft to upgrade from DOS to a system that used a GUI From Newsweek article about Mac: Macintosh Operating System ● Today, Mac is popular in desktop publishing and many educational settings – Some specialized applications only written in Windows ● Apple computers began using Intel processors in mid-2005 – Possible to run Windows on a Mac computer with an Intel processor Apple and Microsoft...together ● 1983 event with Steve Jobs and Bill Gates: http://www.youtube.com/watch?v=NVtxEA7AEHg Microsoft Windows ● Original purpose was to make DOS more user-friendly – Early versions of Windows served as an “interface” for DOS – Windows began with introduction of “Interface Manager” project in 1981 – Windows 1.0 released in November 1985 – Windows 2.0 released in November 1987 – Windows 3.0 released in May 1990 – Didn't become that popular until 1992 with Windows 3.1 (according to book...Wikipedia says that Windows 3.0 was successful...) – What came after Windows 3.1? Microsoft Windows 1.0 ● Released in November 1985 ● “Commercial” (maybe...) for Windows 1.0 by Steve Ballmer: http://www.youtube.com/watch?v=tGvHNNOLnCk ● Screenshot of Windows 1.0 No overlapping windows, could move windows around “like a jigsaw puzzle” (why?) Microsoft Windows 2.0 ● Released in November 1987 ● Had overlapping windows ● Introduced terminology of “minimize” and “maximize” as opposed to “iconize” and “zoom” Lawsuit: Apple vs. Microsoft ● Apple sued Microsoft over interface ● Full name is Apple Computer Inc. v. Microsoft Corporation, 35 F.3d 1435 (9th Cir. 1994) – Lawsuit was filed in 1988 – Lasted four years – Decision “affirmed on appeal” in 1994 – Appealed to Supreme Court; DENIED – Who won? Lawsuit: Apple vs. Microsoft ● Apple claimed that “look and feel” of the Macintosh operating system protected by copyright – Apple claimed that sum of elements more important than each individual element of OS – Judge insisted on analysis of specific GUI elements – Apple came up with list of 189 GUI elements – Judge determined that 179 had been licensed to Microsoft in Windows 1.0 agreement – Other 10 were either unoriginal to Apple or were the only possible way of expressing a particular idea – Court avoided a far reaching “look and feel” copyright ruling by basing ruling on license Apple and Microsoft for Windows 1.0, which wasn't what Apple wanted... Related Weird Al song... ● I'll Sue Ya: http://www.youtube.com/watch?v=LfO9JUNXN7U Other tech-related lawsuits Nintendo vs. Atari Sega vs. Accolade Windows 3.0 ● Windows 3.0 released on May 22, 1990 – First widely successful version of Windows – Significantly changed user interface from Windows 2.0 – Technical improvement made for better memory management with Intel's 80286 and 80386 processors – Included both Reversi and the Solitaire card game Windows 3.1 ● Windows 3.1 – Released on March 18, 1992 – Includes TrueType font system, made windows a serious desktop publishing platform – Included Minesweeper rather than Reversi... Windows 95 ● Intended to integrate previous separate MS-DOS and Windows products ● Make a number of significant changes to interface, including introduction of taskbar at the bottom on the screen ● Introduced with great fanfare – Commercial featuring Rolling Stones song “Start Me Up”: http://www.youtube.com/watch?v=5VPFKnBYOSI – Cyber sitcom with Matthew Perry and Jenifer Aniston: http://www.youtube.com/watch?v=1GWQgb015Lc ● Was the most successful operating system ever up to that point in terms of sales Windows 95 Familiar screenshot... Windows after Windows 95 ● Windows 95 followed by – Windows 98 – Windows ME – Windows XP – Windows Vista – When is Windows 7 coming out? ● General GUI interface introduced with Windows 95 used in all future editions Windows 7 ● Slated for retail release on October 22, 2009 – Focus appears to be on ease of use and performance rather than on “razzle-dazzle” graphics ● Gates has stated that Windows 7 would be more “user-centric” and also would focus on performance improvements ● Microsoft announced that it was using new tracing tools in the development of Windows 7 to measure the performance of the OS in order to locate and then fix inefficient code – According to Wikipedia “Figures released by Amazon.com suggest that sales of Windows 7 during the first eight hours of the pre-order period have already exceeded those of Windows Vista during its 17-week pre-order period” From official Windows 7 site: Note the stress on simplification and ease of use Anyone planning on getting Windows 7? What about a “free” operating system? ● Is there one available? ● GNU (stands for GNU's Not Unix) project began in 1983 with the goal of creating a free operating system – Almost enough available free software available by early 1990s to create full operating system – HOWEVER, there is no free kernel available considered “good enough” to develop a free operating system to compete with Mac and Windows Linux ● Open-source operating system – Originally developed by Linus Torvalds in 1991 – Wanted to use the functions of his new PC with an 80386 processor – Wrote program in order to do so to be “independent of an operating system” – Eventually released that he had written kernel for an operating system ● Has since said that if a GNU kernel had been around, he would not have written his own Linux ● Wrote the following to the newsgroup comp.os.minix: Hello everybody out there using minix - I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things). I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that