Storage
Storage its holds data,instructions and information for future use.
A storage medium is the physical material on which computer keeps data, instructions and information.
- Capacity is the number of bytes a storage medium can hold. For example kilobyte(KB) ,Megabyte (MB) ,Gigabyte (GB) ,Terabyte(TB)
- a storage device is the computer hardware that records or retrieves items to and from storage media
- reading is the process of transferring items from a storage medium into memory
- writing is the process of transferring item from memory to a storage medium
- Access time measures the amount of time it takes a storage device to locate an item on a storage medium and the time required to deliver an item from memory to the processor
- a hard disk that contains one more inflexible , circular platters that use magnetic particles to store data , instructions , and information
- hard disk can store data by using longitudinal recording or perpendicular recording
- the characteristics of a hard disk include capacity ,platters,read/write heads ,cylinders , sectors and tracks ,revolutions per Minute ,transfer rate and access time
- Formatting is the process of diving the disk into tracks and sectors so that the operating system can store and locate data and information
- the hard disk arms move the read and write head which reads items and writes item in the drive
- A head crash occurs when a read and write head touches the surface of a platter
- and always keep a backup of our hard disk
- RAIN is a group of two or more integrated hard disks
- A network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage
- a disk controller consists of a special-purpose chip and electronic circuits that control the transfer of data,instructions,and information from a disk to and from the system bus and other components of the computer
- SATA , EIDE , SCSI , SAS
Flash memory chips are a type of solid state media and contain no moving parts
Solid state drives (SSDs)have several advantages over magnetic hard disk for example faster success time , faster transfer rates , generate less heat and consume less power and last longer
- a memory card is a removable flash memory device that you insert and remove from a slot in a computer, mobile device , or card reader/writer for example compact flash (CF) ,secure digital (SD) , secure digital high capacity (SDHC) ,microSD , microSDHC ,picture card , memory stick and memory stick micri(M2)
- USB flash drives plug into a USB port on a computer or mobile device
- an Express Card module is a removable device that fits in an Express Card slot
- Developed by the PCMCIA
- Commonly used in notebook computers
cloud storage is an Internet service that provides storage to computer users
Optical Discs
an optical disc consists of a flat,round,portable disc made of metal,plastic and lacquer that is written and read by a laser
- it store software,data ,digital photos,movies and music
- it commonly store items in a single track that spirals from the center of the disc to the edge
- Track is divided into evenly sized sectors
- Archive disc-stores photo from online photo center -resolution usually is 7200 pixels per photo -cost is determined by the number of photos that being stored
- picture CD - single-session CD-ROM that stores digital versions of film -it uses a 1024 x 1536 resolution -many photo centers offer Picture CD dervices
- tape is a magnetically coated ribbon of pla stic capable of storing large amounts of data and information
- tape drive is reads and writes data and information on a tape
- a magnetic stripe card contains a magnetic sripe that stores information
- a smart card stores data on a thin microprocessor embedded in the card
- Microfilm and microfiche store microscopic images of documents on a roll or sheet film
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