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DIGITAL STORAGE ( MEMORY), DIGITAL STORAGE, HARD DISKS ( HDD ), OPTICAL…
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DIGITAL STORAGE
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.
server farm
- provide better accessibility
ACCESS
- Accessing a file from Optical disc is the slowest (locally)
- MEMORY is the fastest speed to access a file
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
- Hard disk drive HDD
- Solid-state drives SSD
- memory cards
- USB flash drives
- optical disc
- 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
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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
HARD DISKS ( HDD )
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- 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 )
Q1: The file are capped where inside the sector
OPTICAL DISC
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CD-ROM
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- Can read but cannot write
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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
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 ?
RFID Tag
- the chips can communicate with RFID reader through radio frequency
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