Digital Storage

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Digital Storage by Mind Map: Digital Storage

1. A storage device is the hardware that records and/or retrieves items to and from storage media

1.1. Reading - transfer data from storage medium to memory

1.2. Writing - transfer data from memory to storage medium

2. A storage medium is the physical material on which a computer keeps data, information, programs, and applications

3. A storage capacity is the number of bytes a storage medium can hold

4. Volatile : its contents disappear when power is removed

4.1. Random-access Memory (RAM)

4.1.1. a form of computer data storage that stores data and machine code currently being used

4.1.2. allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory

4.1.3. contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry

5. Non-volatile : its contents remain when power is removed

5.1. Hard disk / Hard Disk Drive (HDD)

5.1.1. Use magnetic particle to store data

5.1.2. Storage capacity determine by :` composition of magnetic coating density no of platter it contains longitudinal / perpendicular recording

5.1.3. Characteristics tracks platters revolutions per minute read/write head always keep backup of hard disk occurs when read/write head touches the surface of platter sectors form factors

5.1.4. Formatting - dividing the disk to tracks and sectors

5.1.5. Solid State Drive (SSD) - flash memory that have its own processor

5.1.6. External hard disk - separate freestanding storage device that connects with a cable to a USB port or other port on a computer or mobile device

5.1.7. Redundant Array of Independent Disks (RAID) - group of two or more integrated hard drives.

5.2. Portable Flash Memory Storage

5.2.1. Memory card - removable flash memory storage device xD picture card SDHC SDXC miniSD microSDHC microSDXC CF M2 Memory stick PRO Duo

5.2.2. USB flash drives plug into a USB port on a computer or mobile device

5.3. Cloud storage keeps information on servers on the Internet, and the actual media on which the files are stored are transparent to the user

5.4. Optical Disk

5.4.1. consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser CD-ROM can be read from but not written to Single-session disc CD-R is an optical disc on which users can write once, but not erase CD-RW is an erasable multisession disc DVD-ROM is a high-capacity optical disc on which users can read but not write on or erase DVD-R or DVD+R are competing DVD-recordable WORM formats, on which users can write once but not erase DVD-RW, DVD+RW, and DVD+RAM are competing DVD-rewritable formats that users can write on multiple times

5.4.2. commonly store items in a single track that spirals from the center of the disc to the edge of the disc

5.4.3. Track is divided into evenly sized sectors

5.5. Enterprise Storage

5.5.1. Allows large organizations to manage and store data

5.5.2. For heavy use, maximum efficiency, and maximum availability RAID duplicates data, instructions and information to improve data reliability

5.5.3. Network Attached Storage (NAS) server that placed on network provide storage to users, computers and devices

5.5.4. Storage Area Network (SAN) high-speed network provide storage to other attached servers

5.5.5. Tape magnetically coated ribbon of plastic store large amount of data and info tape drive reads and writes data and info on a magnetic tape

5.6. Other Types of Storage

5.6.1. magnetic stripe card has a magnetic stripe that contains information

5.6.2. smart card stores data on an integrated circuit embedded in the card

5.6.3. RFID tag consists of antenna and memory chip contains info, transmitted via radio waves RFID reader - reads signal and transfer info to computer/computing devices

5.6.4. NFC-enabled contains NFC chip NFC tag contains chip and antenna that contains info most NFC tag are self-adhesive

6. Access time measure

6.1. Time taken to locate item

6.2. Time taken to transfer item from memory to processor