INTRODUCTION We can divide the parts that make up a computer into three broad categories or subsystem: the central processing unit (CPU), the main memory, and the input/output subsystem. The next three sections discuss these subsystems and how they are connected to make a standalone computer. 1. 2
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Computer chip: A very small pieces of silicon or other semi-conducting material onto which integrated circuits are embedded Circuit board: A thin board containing computer chips and other electronic components Motherboard or system board: The main circuit board inside the system unit All devices must connect to the motherboard External devices (monitors, keyboards, mice, printers) typically connect by plugging into a port exposed through the exterior of the system unit Wireless devices connect through a transceiver or wireless networking technology (like Bluetooth) 5
Central processing unit (CPU): circuitry and components packaged together and connected directly to the motherboard Does the vast majority of processing for a computer Also called a processor; called a microprocessor when talking about personal computers Dual-core CPU: Contains the processing components (cores) of two separate processors on a single CPU Quad-core CPU: Contains 4 cores Typically different CPUs for desktop computers, portable computers, servers, mobile devices, etc. Often made by Intel or AMD 6
The central processing unit (CPU) performs operations on data. In most architectures it has three parts: an arithmetic logic unit (ALU), a control unit, and a set of registers, fast storage locations. 1. 7
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CPU clock speed: One measurement of processing speed Measured in megahertz (MHz) or gigahertz (GHz) Higher CPU clock speed = more instructions processed per second Alternate measure of processing speed is the number of instructions a CPU can process per second Megaflops, gigaflops, teraflops Other factors (CPU architecture, memory, bus speed, amount of RAM, etc.) also affect the overall processing speed of a computer Benchmark tests: Can be used to evaluate overall processing speed 11
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MAIN MEMORY Main memory is the second major subsystem in a computer. It consists of a collection of storage locations, each with a unique identifier, called an address. Data is transferred to and from memory in groups of bits called words. If the word is 8 bits, it is referred to as a byte. 1. 13
Memory refers to chip based storage RAM (random access memory): Computer s main memory Consists of chips arrange on a circuit board called a memory module plugged into the motherboard Stores essential parts of operating system, programs, and data the computer is currently using Adequate RAM is needed to run programs Volatile: Contents of RAM is lost when the computer is shut off Most personal computers use SD-RAM(Synchronous dynamic random access memory) MRAM and PRAM: non-volatile RAM under development 14
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Memory units 1. 16
Word size: The amount of data that a CPU can manipulate at one time Typically 32 or 64 bits Cache memory: Special group of very fast memory chips located on or close to the CPU Level 1 is fastest, then Level 2, then Level 3 More cache memory typically means faster processing Usually internal cache (built into the CPU) Often some cache dedicated to each core; may also have some shared cache accessible by any core 17
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INPUT/OUTPUT SUBSYSTEM The third major subsystem in a computer is the collection of devices referred to as the input/output (I/O) subsystem. This subsystem allows a computer to communicate with the outside world, and to store programs and data even when the power is off. Input/output devices can be divided into two broad categories: nonstorage and storage devices. 1. 20
Magnetic tape CD-ROMs DVDs USB Flash Drive Flash Memory Cards 1. 22
SUBSYSTEM INTERCONNECTION The previous sections outlined the characteristics of the three subsystems (CPU, main memory, and I/O) in a stand-alone computer. We now explore how these three subsystems are interconnected. The interconnection plays an important role because information needs to be exchanged between the three subsystems. 1. 23
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Bus: An electronic path over which data can travel Bus width: The number of wires in the bus over which data can travel Bus width and speed determine the throughput (or bandwidth) of the bus Bandwidth :The amount of data that can be transferred by the bus in a given time period 26
PROGRAM EXECUTION Today, general-purpose computers use a set of instructions called a program to process data. A computer executes the program to create output data from input data. Both the program and the data are stored in memory. 1. 27
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A computer is a system composed of two major components: hardware and software. Computer hardware is the physical equipment. Software is the collection of programs that allows the hardware to do its job. Computer software is divided into two broad categories: the operating system and application programs. Application programs use the computer hardware to solve users problems. The operating system, on the other hand, controls the access to hardware by users. 1. 29
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System software: The operating system and utility programs that control a computer system and allow you to use your computer Enables the boot process, launches applications, transfers files, controls hardware configuration, manages hard drive, and protects from unauthorized use Application software: Programs that allow a user to perform specific tasks on a computer Word processing, playing a game, preparing taxes, browsing the Web, and so forth 31
Application software: Performs specific tasks or applications Creating letters, budgets, etc. Managing inventory and customer databases Editing photographs Scheduling appointments Viewing Web pages Sending and receiving e-mail Recording / playing CDs/DVDs Designing homes Playing games 32
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Multi-programming 1. 34
DOS: Disk Operating System PC-DOS: Created originally for IBM microcomputers MS-DOS: used with IBM-compatible computers DOS traditionally used a command-line interface Can enter DOS commands in Windows 35
Windows: The predominate personal operating system developed by Microsoft Corporation Windows 1.0 through Windows 3.x: Operating environments for DOS Windows 95 and Windows 98: Used a similar GUI to the one used with Windows 3.x Windows NT (New Technology): first 32-bit version of Windows designed for high-end workstations and servers Windows Me (Millennium Edition): designed for home computers, improved home networking and a shared Internet connection 36
Windows 2000: replaced Windows NT; was geared towards high-end business workstations and servers, support for wireless devices Windows XP: Replaced both Windows 2000 and Windows Me Improved photo, video, and music editing and sharing Improved networking capabilities Support for handwriting and voice input Large user base, MS will support until 2014 Windows Vista: Replaced Windows XP with Improved networking and multimedia 37
Windows 7: Newest version of Windows released Oct. 2009 32-bit and 64-bit versions in different editions Home Premium (primary version for home users) Professional (primary version for businesses) Starts up and responds faster than Vista Will run well on netbooks, unlike Vista Device Stage for all connected devices Improved home networking (HomeGroup, etc.) Jump lists, gadgets, etc. -Windows 8 released late 2012 -Windows 8 introduces significant changes to the operating system's platform, primarily focused towards improving its user experience on mobile devices such as tablets to better compete with other mobile operating systems like Android 38
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Mac OS: Proprietary operating system for computers made by Apple Corporation Based on the UNIX operating system; originally set the standard for graphical user interfaces Includes: Safari Web browser New features like Time Machine (For Backup and restore ), Stacks(for file management), Quick Look (image viewer), Boot Camp, etc. More responsive than previous versions 40
UNIX: Operating system developed in the late 1960s for midrange servers Multiuser, multitasking operating system More expensive, requires a higher level of technical knowledge; tends to be harder to install, maintain, and upgrade UNIX initially referred to the original UNIX operating system, now refers to a group of similar operating systems based on UNIX 41
Linux: Version (flavor) of UNIX available without charge over the Internet Increasingly being used with personal computers, servers, mainframes, and supercomputers Is open-source software: has been collaboratively modified by volunteer programmers all over the world Originally used a command line interface, most recent versions use a GUI Strong support from mainstream companies, such as Sun, IBM, HP, and Novell Much less expensive than Windows or Mac OS 42
Windows Mobile: Designed for mobile phones Look and feel of desktop versions Current version 6.1, next version to be called Microsoft Phone. Windows Embedded: Designed for consumer and industrial devices that are not perosonal computers Cash register, GPS devices, ATMs, medical devices and robots. Windows Automotive and Microsoft Auto for cars Ford Sync Android: Linux based OS developed by Open Handset Alliance (including Google) 43
iphone OS: Designed for Apple Mobile phones and mobile devices. BlackBerry Operating System: Designed for BlackBerry devices Palm OS and Palm webos: Designed for Palm devices Symbian OS: Designed for use with smart phones(ex. NOKIA) Embedded Linux: Used with mobile phones, GPS devices, and other mobile devices 44
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Search tools: Designed to search for files on the user s hard drive Windows includes search tools Google, Yahoo desktop search Diagnostic programs: Evaluate your system and make recommendations for fixing any errors found Disk management programs: Diagnose and repair problems related to your hard drive Uninstall utilities: Remove programs from your hard drive without leaving bits and pieces behind Important to properly uninstall programs, not just delete them 46
Clean up utilities: Delete temporary files File compression programs: Reduce the size of files so they take up less storage space on a storage medium or can be transmitted faster over the Internet Both zip and unzip files WinZip (Windows users) and Stuffit (Mac users) 47
Backup and recovery utilities: Make the backup and restoration process easier Backup: Duplicate copy of data or other computer content Good backup procedures are critical for businesses Individuals should back up important documents, e-mail, photos, home video, etc. Store backup data on a CD or DVD, second hard drive, flash memory drive, or upload to the Internet Back up your entire computer once all programs have been installed, so your system can be restored to that configuration. 48
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