Memory, Storage and Media

Question 1

Primary Memory

Answer 1

• Main memory inside a computer
• Directly accessed by CPU, faster access than secondary storage
• both volatile and non-volatile

Question 2

Random Access Memory (RAM)

Answer 2

• primary storage
• is a hardware device
• allows information to be stored and retrieved on a computer
• RAM is a volatile memory and requires power to keep the data accessible
• RAM normally has a larger capacity than ROM

Question 3

Read Only Memory (ROM)

Answer 3

• primary storage
• is a hardware device
• Stores basic start up instructions for a computer e.g. basic input/output system (BIOS)
• Stores bootstrap loader -ROM contains nonvolatile data, meaning it keeps it data even if the device loses power
• Data can be read from and written to RAM, ROM can only be read from

Question 4

Secondary Storage

Answer 4

• non-volatile, persistent memory that is accessed by a device that is part of computer
• not directly accessed by the CPU

Question 5

Hard Disk Drive-HDD

Answer 5

• secondary storage
• HDD is an electromechanical data storage device that uses magnetic storage
• to store and retrieve digital information using one or more rotating magnetic disks

Question 6

Solid State Drive(SSD)

Answer 6

secondary storage
Device that stores data by controlling the movement of electrons within a microchip;
there are no moving parts hence more durable
-Has faster random access
-Has a quick start up/shut down time (reduced latency)
-Is very small
-Is very light
-Consumes very little power

Question 7

Why SSD is replacing HDD

Answer 7

• lower/less power consumption/more energy efficient
• runs quieter
• data access is faster
• occupies less physical space/more compact
• lighter, so more suitable for a portable computer/laptop
• no moving parts so more reliable/durable in a portable computer/laptop

Question 8

Why many web servers still use HDD technology

Answer 8

-HDD is cheaper for larger amounts of storage space
-HDD has greater longevity for read/write functions
`-HDD are trusted technology -No requirement for the increased speed of SSD

Question 9

Offline Storage

Answer 9

• non-volatile memory that can be removed from a computer system
• must be physically connected to computer to obtain stored data
• used to store files as a backup

Question 10

CD(Compact Disk)

Answer 10

• offline storage
• Small plastic disc on which music or other digital information is stored
• in the form of a pattern of metal-coated pits from which it can be read
• using laser light reflected off the disc

Question 11

Digital Versatile Disk(DVD)

Answer 11

• offline storage
• Optical storage media that uses a single spiral track
• uses dual layer technology, allowing high data storage capacity

Question 12

Digital Versatile Disk RAM (DVD-RAM)

Answer 12

• offline storage
• Optical storage media that uses concentric tracks
• allowing writing and reading to take place at the same time

Question 13

External SSD

Answer 13

• offline storage
• similar to internal SSD except it can be easily removed after data has been copied
• connected to computer via USB port while internal SSD is connected via SATA controller

Question 14

Blu-ray

Answer 14

• offline storage
• Optical storage media
• has high storage capacity by using blue laser technology

Question 15

Flash Memory

Answer 15

• offline memory
• Nonvolatile memory chip used for storage and for transferring data
• between a personal computer (PC) and digital devices
• It has the ability to be electronically reprogrammed and erased
• It is often found in USB flash drives, MP3 players, and digital cameras

Question 16

How is digital Media Read and Written in Optical Media

Answer 16

• Red laser is used (blue in case of Blu-Ray), shines onto surface of the disk
• It is rotated at a constant speed to be read
• Surface is covered in a track that spirals from the center
• Data is represented on the surface using pits and lands
• Pits and lands represent binary values
• Pits reflect light back differently to the area in between/land
• Optical device can determine the binary value from the light reflection

Question 17

How is Data Written and Read in Magnetic Media

Answer 17

• surface of magnetic disk/tapes are coated with millions of iron particles
• allowing data to be stored on them
• the surface is divided into concentric tracks, which save data on them
• each track is sub-divided into sectors
• the particles act as magnets when they are exposed to a magnetic field
• magnetic disk/tapes contain read-write heads
• they contain electromagnets that generate magnetic fields
• in the iron particles, as the head passes over them
• a magnetic field’s pull means a binary 1 and a 0 otherwise
• while reading, read-write heads have no magnetic field
• storage medium charges the magnet in head
• causes a current to flow through head based on the polarity
• this way data is sent from read-write heads into the memory

Question 18

How is Data Read and Written in Solid State Media

Answer 18

• store data by controlling the movement of electrons
• within NAND chips -use of NAND only allows to read or erase a block of data at a time
• The data is stored as 0s and 1s in millions of tiny transistors within the chip
• This effectively produces a non-volatile rewritable memory
• also use Electronically Erasable Programmable Read-Only Memory (EPROM)
• main difference is that it uses NOR chips than NAND making operations faster
• EPROM allows data to be read or erased in single byte at a time

Question 19

To calculate file size whose resolution is n x m pixels with w as the colour-depth

Answer 19

-multiply n and m
-multiply product with w color-depth and divide by 8 -convert the answer to kB/MB/GB/TB
(n x m) x w / 8
-to convert the answer from bytes to Kilobytes, divide it by 1024
-to convert the answer from bytes to Megabytes, divide it by 10242
-to convert the answer from bytes to Gigabytes, divide it by 10243