Institute of Business Administration & Information Technology
A+ Computer Hardware
Institute of Business Administration & Information Technology
Storage Devices
Storage Devices
• There are two major classes of computer Storage:
1. Primary Storage or memory (Temporary)
• • •
Temporarily holds data and instructions while processing them Faster to access than permanent storage
2. Secondary Storage or Memory (Permanent) Data and instructions must be copied into primary storage (RAM) for processing
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The human computer
Long Term Storage! Short Term Memory! Processing Information
Input
Output Output
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Primary and Secondary Storage
RAM vs ROM RAM = Memory is lost if power goes out ROM = Memory is more permanent
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RAM: Random Access Memory
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RAM (random access memory) is what is most often referred to when PC memory is discussed. RAM is the form of unstable memory used to hold temporary instructions and data for manipulation while the system is running. The term "random" is applied because the CPU can access or place data to and from any addressable RAM on the system. If power to the system is lost, all RAM is lost as well.
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ROM (read-only memory)
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Generally installed by the vendor of the computer during the process of manufacturing the motherboard or secondary components that need to keep code when the machine is turned off. With the use of ROM, information that is required to start and run the computer cannot be lost or changed.
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RAM Chips
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Type of RAM Modules
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Type of RAM Modules
• SIPP (single inline pin package) module looks like a
rectangular card with a single row of pins along one edge. The SIPP had a very short time in the sun.
•
SIMMs (single inline memory modules) quickly replaced SIPPs, because they are easier to install. 30-pin SIMMs have 30 contacts in a single row
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Installing SIMM (single inline memory modules)
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DIMM (Dual Inline Memory Modules)
• These newer modules look much like SIMMs, but come in
a package with 168 pins and have a different wiring structure, so that one card can form a complete bank. These are the memory packages used on virtually all new motherboards.
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Main memory
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Main memory Installation
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Secondary Storage Floppy Disk
No longer standard
Hard (fixed) disk
500 GB and higher
Removable storage
CD-ROM CD-R/CD-RW DVD/DVD-R/DVD-RW Zip disks Tape
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Hard Drive
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Hard disks are used in all desktop computers, servers, super computers etc. They are also VCR type devices or video recorders that use hard drives instead of tape They store changing digital information in a relatively permanent form. They give computers the ability to remember things when the power goes out.
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HDD
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What is a hard drive?
• The hard drive stores all the computer's information and retains
the information when the computer is turned off. A fast hard drive is needed to supply the CPU with data as fast as it needs it. Hard drive sizes are typically measured in Giga Bytes. The larger the number, the more applications and games you can have installed.
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Removing the cover from the drive
• •
The platters The arm
- typically spin at 3,600 or 7,200 rpm when the drive is operating - holds the read/write heads and is controlled by the mechanism in the upper-left corner - is able to move the heads from the hub to the edge of the drive - extremely light and fast, can move from hub to edge and back up to 50 times per second
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Platters and Heads
• Multiple platters to
increase information storage capacity
• This drive has three
platters and six read/write heads
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Next Class (Tuesday)
• Part II of Secondary Memory (Hard Disk Drive) • Quiz ???????
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All About Hard Drives
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HDD Fail
What causes a hard drive to fail? Here are the causes: • Age - hard drives just grow old and die. • Power failures and power spears. • Viruses can make your hard drive unreadable, or they can corrupt the data so it is unusable. Installing good virus protection is a must but isn't a guaranteed solution against viruses.
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Physical damage. If you drop a hard drive (or the computer it is installed in) you can render the hard drive inoperable. Sometimes just sliding the system across the desk while the system is on can cause severe hard drive problems.
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Protecting Data (Backup)
• Second Hard Drive, This is a practical backup method. It's
quick, but it's still rather costly.
• CD-R/CD-RW … DVD-R/DVD-RW • Online Storage , This is a very new industry that has
emerged since broadband access to the Internet has become more widespread. This system allows you to copy your important data over an internet connection to a web server. You will need to pay for this service, generally on a monthly basis.
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