DIGITAL STORAGE ( MEMORY)

RAM

Read only Memory (ROM)

DRAM & SRAM

is Volatile

Q1: A DVD-ROM Capacity is how much 

 - 4.7 Gigabyte

Measurement

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DIGITAL STORAGE

Definition

  • long-term, permanent access to data & info
  • location where computer keep programs & app

Storage Medium ( secondary storage ) is non-volatile

  • physical material on comp keeps data, info, programs & apps

Most Memory hold data temporarily, it's volatile

  • cloud storage
  • keeps info on servers on internet
  • actual online storage media used is transparent to user
  • storage hardware
  1. Hard disk drive HDD
  2. Solid-state drives SSD
  3. memory cards
  4. USB flash drives
  5. optical disc
  6. tags

Storage Capacity

  • no. of bytes a storage medium can hold
  • 1 kilobyte (KB) = 1024 bytes (B)
  • 1 megabyte (MB) = 1024 KB
  • 1 gigabyte (GB) = 1024 MB
  • 1 terabyte (TB) = 1000 GB

Megabyte Per Second ( MB/s ) = 8 million bits / 1 million bytes

STORAGE ACCESS TIME

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Access time measure amount of time it takes a storage device to locate an item on storage medium.

  • measured in nanoseconds

server farm

  • provide better accessibility

OPTICAL DISC

Blu-ray ROM

20GB (min / disc)

CD-ROM

650MB / disc

DVD-ROM

Digital Versatile Disc (DVD) ROM

4.7GB / disc

Optical disc is one of the secondary storage

ACCESS

  • Accessing a file from Optical disc is the slowest (locally)
  • MEMORY is the fastest speed to access a file

HARD DISKS ( HDD )

41efdece7b0671e8053bf80052948df6--hard-disk-drive-computer-technology

Named as MAGNETIC DISK

  • Actuator Arm is to find the file
  • Power connector is to get electricity
  • A hard disk keep file in Platter
  • A hard disk save their file in track and sector

A) Characteristics


  • tracks
  • sectors
  • platters
  • form factor (size)
  • read n write head
  • revolutions per minute

B ) How HDD keep records of data ?

  • using longitudinal / perpendicular recording

C) Factors to have more storage in hard disk


  • more platters can keep more storage
  • depends on how they do recording (perpendicular can record more file )
  • Density ( how the data closed to each other , it may has high density then can save more file )

HDD interface CABLES

  • IDE ( Integrated device electronic )
  • SATA ( Serial advanced technology attachment )
  • SCSI ( Small computer system interface )
  • Serial attached SCSI (SAS)
  • USB ( Universal Serial Bus )
  • Cable can transfer different speed
  • can transfer rate
  • USB is the slowest
  • SATA is the fastest

Q1: An external hard disk using which cables ?

  • USB

RFID Tag

  • the chips can communicate with RFID reader through radio frequency

Q1: The file are capped where inside the sector

  • Tracks and sector
  • Can read but cannot write

CD-R

  • recorable
  • write once but not erase

CD-RW ( compact disc RE-writable )

  • rewritable
  • can empty the disk & able to write again up to 8 times

Cloud Storage

Infrastructure as a service ( IaaS )

Storage as service ( STaaS )

Desktop as a service

Data as a service (DaaS)

Platform as s service (PaaS)

Bytes per second is a transfer rate

BENEFITS OF SSD ( Solid-state drive )

  • higher storage capacity
  • faster access time & transfer rates
  • more durable
  • longer life
  • lighter weight
  • less heat generation

FLASH MEMORY CARDS

  • CF
  • SDHC
  • SDXC
  • mini SD
  • microSD
  • microSDHC
  • microSDXC
  • xD picture card
  • Memory stick PRO duo
  • M2