Data Storage Flashcards
what is meant be primary storage
directly accessible by the CPU
secondary storage definition
not directly accessed by CPU - more permanent data storage
what is RAM used for
- temporarily store instructions + data whilst computer in operation
- copied from hard disk into main memory
is RAM volatile or non-volatile and why does it mean
Volatile - gets wiped as soon as power switched off
is ROM volatile or non-volatile and why does it mean
Non-volatile - Data permanently retained without power
what does ROM stand for
Read Only Memory
can ROM be overwritten
NO: read-only
- cannot be changed after being set by manufacturer
what is ROM memory used for
- computer start up instructions
- embedded systems
what storage types does secondary storage include
- Hard drives
- USB flash drives
- CDs
is secondary storage volatile or non-volatile
non-volatile
what is secondary storage best for
longer term storage of files + data - will remain when power off
what type of storage media would you use in a laptop or tablet device. and why?
Solid State Drives (SSDs):
- require very little power
- create little heat - lack of moving parts –> small + reliable
- portable
what are the adv of SSDs over HDDs
- 100x faster
- do not require expensive cooling equipment
where are SSDs used
- laptops
- tablets
- smartphones
- desktop + larger computer systems
what are the adv of HDDs
- cheaper
where are HDDs often used
Desktop computers
what are USBs best used for
regular backup of small files - more durable
what are CDs and DVDs used for
for music + video storage in short + medium term - 10-25 yrs
describe the operation of SSDs
- uses NAND or NOR gates in electrical circuits to store data
- these use transistors as control gates and floating gates to control flow of current
- current flowing = 1, no current = 0
how do optical drives work (CDs / Blu-ray)
- uses laser to reflect light off the surface of the disk
- one long spiral track contains pit and lands
- when laser beam hits curved start or end of pit –> light refracted and 1 recorded
- where light reflected back directly from flat pit / land = 0 recorded
describe the operation of a HDD
- data stored on magnetic patters , divided into tracks and sectors
- Data is read and written
using electromagnets - iron particle on disk magnetised to be either north or south = 0 or 1
what are the moving parts in a HDD
- drive read/write head moves into position - movement takes time
- drive spindle rotates disk
what are the disadvantages of moving parts
- easily damaged + issues if dropped
- overheating
what is virtual memory
small section in hard disk used when not enough space in RAM for all programs + data currently working on
describe the process when data needs to be moved into the virtual memory. Example using Windows, Word, Word document
- Windows, Word, Word document opened and loaded into RAM from the hard disk
- fills up RAM
- if Excel required, CPU must first transfer pages of data that compromise Word out of RAM into virtual memory - to free up space
- RAM is divided into fixed sized pages (4KiB)
- file currently in RAM may be help in several non-contiguous pages
what saves the number and location of each page
page table
what is cloud storage
remote file storage - accessed remotely in comparison to storing data locally
- often include *major 3rd party - Google, Microsoft
what is needed for cloud storage
Physical servers + storage
Adv of cloud storage compared to local storages
- No need to purchase local storage devices / employ maintenance staff
- online storage can shrink or grow as you need it
- greater fault tolerance - all hardware + backup issues handled externally
- Remote access to files from any Internet connected device - anywhere in world
- enables file sharing + collaboration
- more environmentally friendly
Disadvantages of cloud compared to local storage
- may need annual subscription
- Backup + restore may be slower depending on internet connection speed
- security of data managed by 3rd party - outside of user’s control
- need internet connection
- your responsible for security breaches over data - even though you have no control over security
what does NIC stand for
Network Interface Cards
what are NICs used for
NICs are physical component required to connect to any network enable device - e.g. home computers, smartphones, printers
what are NICs
a physical component needed to operate with wireless connection or wired connection using Ethernet cable
what is a MAC address
- used to identify device with unique hexadecimal identification number
- assigned to every network interface card used in networked devices
will MAC address change
NO
- IP address may change
- MAC address is set by the manufacturer and is static - same forever
hat do the first 3 bytes represent in a MAC address
unique manufacture’s code
hat do the last 3 bytes represent in a MAC address
unique serial code
