memory & storage Flashcards
(22 cards)
Why is primary storage needed
To hold data and programs that are currently in use by the CPU
What is RAM and what are it’s characteristics
Random access memory
-volatile, data is lost when the power is turned off (temporary memory)
-it’s used to store user data, programs, and parts of the operating system currently in use
- memory can be written to or read from
What is ROM and what are its characteristics
Read only memory
-non-volatile, data is not lost when power is turned off (permanent memory)
-it’s used to store BIOS and the bootstrap loader which is required at the start-up of the computer
-memory can only be read from and not written to
Why is virtual memory needed
When the RAM runs out of space, the operating system starts using part of the secondary memory to store data temporarily. This is known as virtual memory
How does virtual memory work
-a process running on the computer may need to store data in the physical memory
-if there is no free memory, the memory manager will ‘swap out’ some of the least recently used data stored in RAM to the swap area in the Hard Disk Drive and ‘swap in’ the requested data to the now free area
-(if the swapped out data is needed again it is swapped back in at the expense of the other data)
Why do computers have secondary storage
So all the data on the computer can be stored when the power is switched off
How does magnetic storage work? Give examples
Mechanical parts move over the disks to read and write data magnetically
E.g hard disk drive
What are the advantages of magnetic storage
Advantages:
-large storage capacity
-fast access to read and write data
-fairly inexpensive to manufacture
-cheap to buy
What are the disadvantages of magnetic storage
-data can be lost or altered by magnetic field or mechanical problems
-can suffer wear and tear due to moving parts
What is optical storage? Give examples
Uses a lens and a light beam to read & write data onto a disk. Examples: CDs, DVDs, and Blu-ray disks.
What are the advantages of optical storage?
Small and light - portable
Cheap to manufacture
Durable - they can store data for long periods safely
What are the disadvantages of optical storage?
Some formats mean that data cannot be overwritten
What is solid-state storage? Give examples
Uses flash memories to store data. Examples: solid-state drives, SD cards, USB memory sticks.
What are the advantages of solid-state storage?
Faster boot-up as they have no moving parts
Can be made to be very compact in size
Large storage capacity
More robust than magnetic due to having no moving parts
What are the disadvantages of solid-state storage?
Expensive to manufacture
Have a limited number of times that data can be written to and read from
Rank storage types from smallest to largest capacity.
CD (700 MB)
DVD (4.7 GB)
Blu-ray (25GB / up to 128GB)
SSD (Up to 1TB)
HDD (Up to 8TB)
USB flash drive (Up to 1TB)
Rank storage types by speed (fastest first).
SSD
HDD
USB flash drive
Blu-ray disk
DVD
CD
Which storage types are the most portable?
Optical (CD/DVD/Blu-ray) & Solid State Storage (SSD, USB flash drives).
Compare the cost of storage types.
Optical disks: Very low cost.
HDDs: Cost-effective (low cost per GB).
SSDs: More expensive.
Which storage types are the most durable?
Optical disks: Very robust.
Solid State Storage: More durable (no moving parts).
Compare the reliability of HDDs vs. SSDs.
HDDs: Reliable unless exposed to extreme conditions.
SSDs: More reliable (no moving parts, less prone to mechanical failure).
Rank file types by typical size (smallest first).
Text
Sound
Pictures
Movies (largest)