CHAPTER 8 = SECONDARY STORAGE

SECONDARY STORAGE 

•        Secondary storage devices are used to save, to back up, and even to transport files consisting of data or programs from one location or computer to another. 

•        Secondary storage devices have always been an indispensable element in any computer system.

•         Secondary storage provides permanent or nonvolatile storage.

•       Some important characteristics of secondary storage include:

1.     Media are actual physical material that holds the data and program.

2.     Capacity measure how much a particular storage medium can hold.

3.     Storage devices are hardware that reads data and programs from storage media.

4.     Access speed measure the amount of time required by the storage device to retrieve data and program. 

 

HARD DISKS

• A hard disk drive (HDD) is a non-volatile , random access device for digital data. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the platters. 

• Introduced by IBM in 1956, hard disk drives have fallen in cost and physical size over the years while dramatically increasing in capacity. Hard disk drives have been the dominant device for secondary storage of data in general purpose computer since the early 1960s. They have maintained this position because advances in their areal recording density have kept pace with the requirements for secondary storage. Today's HDDs operate on high-speed serial interfaces; i.e., serial ATA (SATA) or serial attached SCSI  (SAS).           

Components  

• A typical hard disk drive has two electric motors; a disk motor to spin the disks and an actuator (motor) to position the read/write head assembly across the spinning disks.

• The disk motor has an external rotor attached to the disks; the stator windings are fixed in place.   

• For more information refers to http://en.wikipedia.org/wiki/Hard_disk_drive     

INTERNAL HARD DISK   

• It is located inside the system units. 
• The are designated as C drive. 
• Are able to storage and retrieve large quantities of information quickly. 
• Used to storage program and large data files.                                                
    
   
  http://www.blogger.com/goog_227295440
  
  
  EXTERNAL HARD DRIVE     
  • Provide fast access, they have a fixed amount of storage and cannot be easily removed from the system cabinet. 
  • Typically connect to a USB or FireWire port on the system unit, are easily removed and effectively provide an unlimited amount of storage. 
  • For desktop computers have typically capacities of 20 to 500 GB. 
  •   Credit card-size hard disks cartridges called PC Card hard disks are available for notebook computers with typically capacities up to 5 GB.

 

http://www.build-your-own-computer.net/external-hard-drive.html

Secondary storage are important because can be used to restore a backup of your files if you have to format. It also can be bring it with you if you need to access files at work or somewhere else. Without secondary storage you would lose all of you data every time your computer powered down. In order words , your computer would not have anywhere to save data indefinitely. For more information you can refers to http://wiki.answers.com/Q/Why_secondary_storage_devices_are _important.                                                                                                                            

Citation ~ http://wiki.answers.com/Q?Why_secondary_storage_devices_are_important.       

~http://en.wikipedia_org/wiki/Hard_disk_drive                                       

~Computing Essentials 2010 Books                                                        

CHAPTER 7 : INPUT & OUTPUT

Image Chapturing Devices

Reference Information from Computing Essentials Complete 2010 :

• Optical scanners is tradisional copy mechines, make a copy from an original.
• Exp : digital copy of a photograph
• Image Capturing Device can create & capture original images.
• Exp : digital cameras, digital video cameras
• Captured image data and the time spatial parameter corresponding thereto to be stored in the storage server @ recorded on the recording medium.
• Captured image data and the time spatial parameter corresponding thereto are supplied to the image data processing unit in the holographic stereogram producing device.
• Time spatial parameter is used as a second time spatial parameter which is required at the time of producing a holographic stereogram.
• For more information you can search in http://www.freepatentsonline.com/7256783.html

(1) Digital Camera

• Images are recorded digitally on a disk @ camera's memory and then downloaded @ tranferred to computer.
• View it immediately.
• a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor.
• Digital camera can do things film cameras cannot: displaying images on a screen immediately after they are recorded, storing thousands of images on a single small memory device, and deleting images to free storage space.
• Digital cameras are incorporated into many devices ranging from PDAs and mobile phones (called camera phones) to vehicles.
• For more information you can search in http://en.wikipedia.org/wiki/Digital_camera

http://gadgetophilia.com/c/digital-camera/page/4/

 http://www.conita.com/Digital-Cameras/Nikon-Digital-Cameras/

(2) Digital Video Camera

• Record motion digitally on a disk @ camera's memory.
• WebCams : capture images & send to computer for broadcast over the internet. It is designed to be attached to the computer monitor.
• Connected with the computer network via USB port or sometimes with ethernet and wi-fi.
• Its usages are seen in video telephony, recording of video files and still-images which one can access through many software applications and devices.
• Webcam has made possible for internet users to see famous TV , which was quite popular across the globe.
• Webcam is good source for deaf and speech-impaired individuals.
• For more information you can search in http://hubpages.com/hub/Webcam-means-video-capturing-device
  
  
                        http://www.willshops.com/samoon-hd-dv200-high-definition-digital-video-camera-dvc-p-1458.html
  
  
  
  
  
  
  
  http://www.techshout.com/gadgets/2006/24/g-shot-dv815z-a-feature-rich-multi-functional-5-in-1-digital-video-camera-unveiled-by-genius-in-india/
  
  
  
  
  
  Summary :
  Nowaday many people use the digital camera to capture their beautiful picture. Image capturing device is a easy material to use it and it is a convinient to give us to bring it to anywhere, such as go traveling. Image capturing devise is a moden camera, it is have more advantage than the old ones, film camera. 

Citations : - http://www.freepatentsonline.com/7256783.html
                 - http://en.wikipedia.org/wiki/Digital_camera
                 - http://hubpages.com/hub/Webcam-means-video-capturing-device