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Storage Devices

Storage Devices. By : Reem Hasayen. Storage device. A storage device is a hardware device capable of storing information. There are two types of storage devices used in computers P rimary storage device such as RAM and Cache 2. Secondary storage device

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Storage Devices

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  1. Storage Devices By : ReemHasayen

  2. Storage device A storage deviceis a hardware device capable of storing information. • There are two types of storage devices used in computers • Primary storage device such as RAM and Cache 2. Secondary storage device such as a computer hard disk drive

  3. Primary storage device • Also known as internal memoryand main memory. • primary storage is a storage location that holds memory for short periods of times while the computer is on. For example, computer RAM and Cache.

  4. Compare between RAM and hard drive • RAM 1. Smaller amount (typically 128MB-1 GB) 2. Temporary storage of files and programs. 3. Contents disappear when you turn off power to the computer. 4. Consists of chips ( microprocessors) • Hard Drive • Much larger amount (typically 1 GB- 400 GB ) • Permanent storage of files and programs. • Contents remain when you turn off power to the computer. • Consists of hard disks ( platters)

  5. Compare between RAM and hard drive • RAM 5. Contents are stored electronically in bits on the chips, in electronic offs and ones (0’s and 1’s),so RAM needs electrical power to hold information. • Hard Drive 5. Contents are stored magnetically, also in bits which are offs and ones or (0’s,1’s),so the hard drive does not need power to hold information.

  6. RAM • This type of memory has 4 fundamental features: • Speed. • Capacity. • Volatility. • Random.

  7. Speed • Information in RAM is stored based on electrical signals….so to change information simply requires sending different electrical signal to the chip. This happened very fast. • Using the hard drive need to move a physical object “ head” that is spinning to the right position, this is very slow

  8. volatility • This mean that data loaded into RAM is only stored temporarily until the PC is turned off

  9. RAM • Advantages : Fast • Disadvantages: 1. “Forgets” when you turn the computer off. 2. more expensive than the hard drive storage.

  10. Cache memory • This memory is an ultra fast memory that allow the CPU to perform certain operation in very brief period of time. • It takes information from RAM memory and send it directly to the CPU to be executed.

  11. Secondary storage Hard Drive • The hard drive also called “Storage” or “ Disk Space” and its measured by (MB) or (GB) • Hard drive consist of a metal platter which spin very fast. • As it spins the hard drive head moves along the platter and can read and write information.

  12. Hard drive • Advantages: 1. relatively cheap. 2. can turn off the computer and reload the information later • Disadvantages: since it’s a mechanical device( spinning platter) it can be slow.

  13. Hard drive

  14. What affects hard drive speed • Spindle Rotation Speed • Seek Time

  15. How hard drive store information • On each of the platters there is a thin layer of magnetic film. • Data storage on hard disks is very similar to that of a cassette tape. • Data is stored in many 1's and 0's. These binary digits are arranged in different ways to represent different characters.

  16. Cache memory • http://www.youtube.com/watch?v=4McNhpkDNpQ

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