8/18/2008 1 Chapter Three ? Operating Systems: Understanding the Platform ? Operating Systems An operating system is a collection of computer programs that administer the hardware and software of a computer so they work properly. One of the main tasks of these system programs is to load the operating system (OS). Many times operating systems are referred to as platforms . Some of the most widely?used platforms are Microsoft Windows, UNIX, Linux, and Mac OS. Most operating system functions run with little or no user interaction. Once an OS (system software) is up and running, the computer user can use application software like Microsoft Excel and Adobe Photoshop. Chapter Three ? Operating Systems: Understanding the Platform ? Processes / Multitasking A job or task a computer performs is called a process. When a computer can run more than one process at a time it is referred to as multitasking. Sharing data from one application software to another without both running at the same time is technically feasible but very inefficient , . Press the ?Alt? and ?Tab? keys at the same time to see what applications are running. Chapter Three ? Operating Systems: Understanding the Platform ? Memory Management and Storage Operating systems coordinate and arrange the computer?s memory, which includes cache, random access memory (RAM), registers, and virtual memory. The operating system also facilitates disk storage. Memory retains digital data and information in a variety of ways. CPU Cache is small, very quick memory because it stores copies of information and data from the most regularly used parts main memory CPU cache helps . decrease the time it takes to access memory. Random Access Memory (RAM) is primary storage. RAM is a type of storage that allows stored data to be accessed in any (random) order without physical movement of the storage media. RAM is considered volatile memory because its contents is lost if it is not saved to a non?volatile device. 8/18/2008 2 Chapter Three ? Operating Systems: Understanding the Platform ? Memory Management and Storage Registers are extremely fast very small amounts of memory used to quicken the implementation of computer programs by providing access to commonly used calculated values. Virtual memory is memory the operating system uses to coordinate, track, and efficiently allocate the use of CPU cache, registers, RAM, and disk storage. Virtual memory is actually a technique that lets application programs like a spreadsheet use fragmented pieces of memory and makes it easier for large applications to use physical memory. Disk storage is non?volatile, secondary storage that is recorded to a physical device, like a hard drive or optical disk with a read/write apparatus. Chapter Three ? Operating Systems: Understanding the Platform ? Disk Management Operating systems are responsible for reading and writing data and information onto a disk, typically a hard drive, optical device, or a solid state storage device. The OS needs to be able to save, or write information to a disk in the most efficient manner possible so it can be read files efficiently and therefore quickly. Disk management is facilitated (Microsoft platform) by creating a ?table of contents? for the disk called a file allocation table, or FAT. The FAT directs the read/write arm of the hard drive to where data exists and accesses it. Defragmentation is a program that reorganizes the hard disk. Files and folders still reside in the same place, but with the ?clutter? removed, and therefore, the disk can perform more efficiently Chapter Three ? Operating Systems: Understanding the Platform ? File Management All operating systems feature file management; a way to store and organize a user?s work represented by computer files to the memory of a computer. Operating systems are made up of a hierarchy of directories, (more commonly called ?folders?). Microsoft Windows ® represents its file management system visually with a graphical user interface (GUI) environment A file manager is a computer program . that displays a user interface to work with file systems. Files are displayed in a hierarchy, in a computer system, sometimes called a tree. A hierarchy is a way to rank and organize files. 8/18/2008 3 Chapter Three ? Operating Systems: Understanding the Platform ? Networking Computers that are not connected to any other computer are referred to as stand?alone. When a computer is connected to one or more computers it is called a network. Operating systems need to be able to offer networking, and do so through a set of rules called transmission control protocol and Internet protocol (TCP/IP). TCP/IP is simply a set of rules for transferring information from one computer to another. TCP/IP breaks up files into packets and passes them from one computer to another. When the packets arrive at a networked or receiving computer, TCP/IP ensures that the files are intact and usable by rebuilding the packets into the original file. Chapter Three ? Operating Systems: Understanding the Platform ? Device Drivers Operating systems are in charge of device drivers that are computer programs that allow peripheral hardware devices like printers or scanners to interface with a computer system and work properly. Operating systems have Plug?and?Play, which is preloaded and configured drivers that peripheral manufacturers have previously supplied to the operating system manufacturer so when a new device is detected no driver , , installation is necessary, because it is already loaded on the operating system. In 1996, Universal Serial Bus (USB) ports were developed and gained traction with Microsoft and today are considered a standard, and essentially use the same drivers that many other manufacturers employ. Chapter Three ? Operating Systems: Understanding the Platform ? Graphical User Interface A Graphical User Interface (GUI) is a presentation on a computer monitor that allows a user to interact with a computer and the devices connected to it. Many GUIs have icons, and other visual indicators like menus that launch programs like PowerPoint, documents, and many other requests from a user without having to issue programming commands with the click of a pointing device. 8/18/2008 4 Chapter Three ? Operating Systems: Understanding the Platform ? Embedded Operating Systems Many devices and appliances that rely on computing need embedded operating systems, like cash registers, automatic teller machines (ATMs), microwave ovens, and specialized handheld devices. Embedded computing refers to a computing system or device that performs a dedicated function. In most cases, these systems cannot be modified by the end user . Embedded operating systems are highly modified, basically stripped down version of larger operating systems that manufacturers produce for specific tasks and devices, like a Blackberry ® , Microsoft Pocket PC ® , or an iPhone. Chapter Three ? Operating Systems: Understanding the Platform ? Major Operating Systems Windows is a proprietary graphical user interface?based (GUI) operating system developed by Microsoft Corporation. Mac OS is a proprietary graphical user interface?based (GUI) operating system developed by Apple Inc., formerly Apple Computer. UNIX is a proprietary operating system developed in the 60s and 70s Bell Labs . Linux was originally started by Linus Torvalds and is a non?proprietary UNIX?like computer operating system. Chapter Three ? Operating Systems: Understanding the Platform ? Open Source Operating Systems Open source software is when software?s source code or programming is open to anyone who cares to access and perhaps even modify it. Microsoft Windows Vista ® is considered proprietary software. Linux is considered non?proprietary or open source software. 8/18/2008 5 Chapter Three ? Operating Systems: Understanding the Platform ? File Management Picture of GUI File Manager Return mjmccart Microsoft PowerPoint - Chapter3
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