Computer Boot Camp: How Do Computers Work? Donald Nelson, M.D. Gordon Baustian, M.D. Ron Reider, M.D. Introduction Computer functional parts Computer Software / Operating systems File systems - files and directories Using Windows Explorer The Computer’s Parts Central Processing Unit (CPU) Memory Input/Output (I/O) Devices Secondary Storage Central Processing Unit (CPU) The “brain” of the computer Can manipulate and change information in memory Usually a single “chip” (integrated circuit) “Pentium II” “AMD K7” The Central Processing Unit (CPU) Control Unit / Sequencer • Fetches and interprets instructions from the memory • Directs the execution of program instructions Arithmetic/Logic Unit (ALU) • Modifies data in response to program instructions • Add, subtract, multiply, compare, etc. Computer Memory Stores the information that the computer manipulates Stores the programs that manipulate the information Computer can manipulate both DATA and PROGRAMS • von Neümann architecture Computer Memory RAM - Random access memory • Read-Write ROM - Read only memory • Stored information doesn’t change Memory: Organization All data in the computer are stored as binary numbers (composed of 1’s and 0’s) Memory is array of storage locations Each location designated by a number (address) Each location contains a number (data/content) Memory: Organization CPU <> Memory Interaction Memory: Described by the number of locations (addresses) available the number of binary digits (bits) stored at each location Usually 8digits (8 bits = 1 byte) at each address Memory Size 1 Kilo = 1024 (210) locations 1000 1 Mega = 1,048,576 (220) locations 1,000,000 1 Giga = 1,073,741,824 (230) locations 1,000,000,000 64MB = 67,108,864 bytes = 536,870,912 bits The Computer’s Parts Input / Output Devices (I/O devices) • Allow interaction with us (users) • Allow interaction with other systems • Convert between external representation (character, image) and the internal representation (binary numbers) used in the computer I/O Devices: examples Display screen (CRT or LCD) Keyboard Pointing device (mouse / touch pad) I/O Devices: examples Printer Scanner Microphone, speakers Modem Network interface card (NIC) Infrared port The Computer’s Parts The Computer’s Parts Secondary Storage • Hard disk drives • Floppy disk drives • CD / writable CD • Tape drives • Etc. Primary vs Secondary Storage Fast Slower Random access Indirect access Volatile Non-volatile Expensive “Cheap” Limited storage High storage capacity capacity Primary vs Secondary Storage Data the computer manipulates must be in primary memory at the time Data in primary memory go away when power is off Primary vs Secondary Storage Stores more data than primary memory can hold Stores programs and data between uses without consuming power Serves as backup (can keep extra copies of important info) The Computer’s Parts Secondary (disk) storage Disks store blocks of bytes much larger than individual memory locations Secondary (disk) storage (Whew!) Time to change focus Most of the time, you won’t have to pay attention to any of this while you use your computer The computer’s software hides the gory details from the user The Operating System System Software System Software is necessary to make the computer work. • Operating Systems • Utilities Application Software programs accomplish the user’s tasks • Word Processors • Spread Sheets Medical Records Operating System provides a way to boot (start) the computer control of the computer hardware: keyboard, display, mouse, printer a file system, a way to name and organize files for storage on disk, hence Disk Operating System (DOS) Operating System provides a way to load and run user (application) programs a way for application programs to use the hardware devices and file system Operating System provides a “User Environment” a consistent way for application programs to interact with the user Much of the UI is provided by Windows, not by individual programs Windows 95 / 98 have a Graphical User Interface (GUI Interface) The Graphical User Interface GUI: “gooey interface” The “WIMP” Interface • Windows • Icons • Menus • Pointing device (mouse, etc.) “Point and Click” Chewy (CHUI) or Gooey (GUI)? Operating System may provide multiple users - several people may use the computer at one time security - to prevent individual programs and users from interfering with each other Examples: UNIX Linux Windows NT with MetaFrame The File System A key function of the Operating System is to manage storage on the disk A file system lets programs and users manage items on the disk as named files rather than physical locations The O/S keeps track of the physical location of the files for us The File System A DIRECTORY kept by the operating system • Keeps track of each file’s name • Contains information about the file’s physical location • May keep additional information such as date created, etc. The File System Special files (subdirectories) are themselves directories Directories may contain subdirectories, nesting to multiple levels Hierarchical directories Drive C: \ [root] My Documents Program Files Windows Hierarchical directories Drive C: \ [root] My Documents Program Files Windows Desktop Start Menu System Windows file naming Four part names • Drive (or device) • Path • File name • File type (extended name) C:\Windows\System\WinTrust.hlp C:\Windows\System\WinTrust.hlp C: = Drive (hard disk named C:) \Windows\System\ = Path • begin in “\” (root) • go to “Windows” subdirectory • go to “System” subdirectory of Windows WinTrust = File Name hlp = File Type (help file) \\FPC- WTS01\Install\Meditech\Install.exe \\FPC-WTS01 = Device (network host named FPC-WTS01) \Install\Meditech\ = Path (subdirectories) Install = file name exe = file type (executable program file) Windows file naming Depending on the context, some or all four parts of the file name may be optional Directories are also known as folders Windows explorer allows visual browsing through the file system Find function allows you to locate files without knowing the directory Windows file types Identify the kind EXE - program (executable of file file) For data files, COM - command identify the DOC - MS Word document application that PPT - PowerPoint usually opens presentation the file XLS - Excel spreadsheet HLP - Help file Shortcuts Have LNK file type Create a “dummy” file in one directory that refers to an actual file elsewhere Effectively, the same file can exist at multiple locations in different directories Allow you to organize your files independent of their actual locations Drill and Practice Open Windows Explorer Use it to find “WinTrust.hlp” by browsing Use the Find|Files or Folders function to locate the same file Click it to see what happens Drill and Practice Explore your C: or D: drive Create a subdirectory named “Shared” in the root directory Create a shortcut to the “Shared” folder and place it on your desktop Setting up your own directories \ [root] My Documents Drive C: or D: CRMEF Handouts Internet Letters Personal Projects Setting up your own directories Setting up your own directories Setting up your own directories THE END Try it for yourself.
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