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Chapter 3: Where are programs and data Stored?
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How important is this chapter to understanding how a computer works? 7 (on a scale of 1-10 with 10 being most important.
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How important is this chapter to understanding how to use a computer? 5 or 6
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Memory and Storage Usage Von Neumann Architecture – when a program is running it must be contained in memory at that time. Storage is the place where “stuff” is kept when it is not being used.
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Types of Memory RAM – random access memory Used for running programs and manipulating data ROM – read only memory Contains startup commands and specialized software firmware
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Types of Memory (continued) CMOS Contains configuration information Registers Inside the CPU where the data is actually manipulated Cache Used to speed up processing Buffers
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Types of Storage Disk Magnetic Hard disk (fixed disk) Floppy disk Removable disk Optical CD rom DVD rom CD-R/CD-RW/DVD-R/DVD-RW …
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Types of Storage (continued) Tape Open reel Cassette Used mostly for backup Integrated Circuits Flash Memory
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Memory and Storage Characteristics Memory is volatile Transitory is the term used by the book. Storage is permanent (where permanent means a long time but not forever)
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Physical Characteristics of Magnetic Disks Platters Individual disks Tracks Concentric circles Sectors Pie shaped wedges Blocks Intersection of a track and a sector
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Physical Characteristics of Magnetic Disks (continued) Clusters The smallest number of blocks that can be accessed at one time Cylinders “Vertical” collections of tracks. Difference between optical and magnetic
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Logical Organization of Disks Bootable disks and boot records Disk directory Subdirectories File allocation schemes Data area
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Virtual Memory Using Storage as memory disk only Increases capacity but decreases speed Paging Thrashing
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Data travel during processing discuss
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How much memory is enough? It depends What Operating System? What do you do? How much data do you manipulate?
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No really, how much memory do you need? My experience Based on current O/S (Windows XP) Based on current prices of memory (Sept 2005) One 256mb chip = 25 dollars Based on current applications… 512mb or 1024 mb
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Deleting a file vs. Erasing a file Note I have never heard these terms used in this manner. Nonetheless… How to remove Mark directory Mark data area Overwrite data area
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Fragmentation Occurs after lots of use of a disk Defragmentation will generally speed up disk access because the head will not have to move as much during reading and writing Do it occasionally (monthly) Time consuming
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Protecting Your Computer Viruses Intrusion Privacy
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Viruses You should have an up to date virus detection and removal program on your computer. The U’s standard is McAfee VirusScan version 8
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Intrusion Your computer should have a reliable firewall system. There’s one built into windows which protects your system from incoming but does not protect it from outgoing. I use Zone Alarm Pro which protects from both. There are lots of other good programs Learn how to recognize Firewall problems
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Privacy Spyware Added to your system when you surf or install “free” programs Spybot Search and Destroy is my choice Adaware is also popular.
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