1.1.3

• hardware are physical components of a computer such as: 4

  primary storage

  secondary storage

  input/output device

  processors
• magnetic storage(mostly HDD)(hard disk drive)

  what is a platter

  positive and negative charged magnetic particle are part of magnetic disk called the platter
• MS(magnetic storage)

  where can data be stored

  data can be stored anywhere on the disk, so to read/write data, we need to find the location of the disk
• MS

  A magnetic read/write head is used to...

  access to data while the platter spins
• what are 4 properties of magnetic media

  good reliability(tends to last a long time)

  low cost

  low speed(the high number of moving parts make magnetic media slow to access)

  high capacity
• what are computer systems made from

  are made of hardware and software which work together
• what are the 3 main types of secondary storage

  hard disk drive(HDD)

  solid state drive(SSD)

  compact disk(CD)
• what are the two types of computer system

  embedded systems

  general purpose systems
• what are the two types of primary storage

  RAM, and ROM
• what is secondary storage

  is the memory in which the computer can store data or instruction which are NOT currently in use
• what is primary storage

  is the memory in which the computer can store the data or instruction that are currently in use.
• what is general purpose systems

  example:smartphone

  are capable of performing many different tasks
• what is the disadvantage of magnetic media

  not robust(means that a device will not be damaged by shocks)

  slow access time
• what do input/output device allow

  example:2

  allows users to input data into the computer, or receive a data output from the computer

  example:keyboard,mouse
• what are the 4 properties of flash memory

  -usually fast to access(because it does not have any moving parts)

  -can be re-writable(a certain number of times before it starts to degrade)

  -robust(not easily damaged by shocks or vibrations)

  -non-volatile(keeps content when power is switched off)
• what are the uses of flash memory

  ROM chips

  SSD(solid state drive)-used at home becuase of the performance

  SD(secure digital)-often used to extend the capacity of devices such as cameras and phones (provide high capacity, good for small devices)

  cameras
• how does optical storage access data

  a laser is shone on the disk surface, if the laser hits the land, it will be reflected into the sensor, if hit on a pit, it will be reflected elsewhere
• what are the 2 types of optical storage and what they do

  Blu-ray disk(BD)-used to store high definitation movies or games

  digital versatile data(DVD)-store games or standard definition movies for home views
• what are the properties of optical media

  low speed

  gtreat reliability(waterproof, shockproof)

  low cost
• what are the types of optical disks

  ROM, write once(R)
• what does optical storage use to retrieve data

  uses laser light to retrieve data from the surface of optical media
• what is a microscopic hole called

  a pit
• what is RW

  the disk can be overwritten whenever the user would like to
• what is the flat surface of a disk called

  the land
• what is the R

  once the user has written data to the disk, they cannot overwrite it
• what is the ROM

  the manufacturer writes the inital data and this cannot be changed
• why might optical media be low speed

  because the parts in the optical media drive have to move to find the right bit of data on the disk, access times can be quite slow
• is RAM cheaper or expensive per capacity than secondary storage media

  expensive per capacity than secondary storage media
• RAM is volatile. what does it mean

  that it will lose its content when power is lost(when the computer is switched off)
• ROM is made from flash memory therefore...

  content cannot be changed easily
• ROM is non-volatile, what does that mean

  keeps its content when power is lost
• ROM, is it fast, is it expensive

  yes, yes

  fast but expensive
• what are the 2 types of memory

  ROM

  RAM
• what does random access mean


  that any part of the memory can be accessed as qucickly as any other part of the memory
• how does virtual memory work,

  move parts to hard disk drive(HDD)

  what do we do if page is not used

  than we put it into virtual memory
• how does virtual memory work,

  what is paging

  memory that is split into sections
• moving pages to RAM

  when we want to use a page again...

  we need to move it back to RAM
• virtual memory works by moving these pages...

  between the RAM and the secondary storage
• want to see a page again, we need to move it back to RAM, how is this done

  this is done by swapping the page that we want with one that is already in the RAM
• what are the disadvantages of virtual memory

  -can have negative impacts on the performance or on health of solid state drive(SSD)

  -Might have limited space in secondary storage