1.2 Memory and Storage Flashcards
What does increasing the capacity of RAM do to increase performance
Less likely to use the slower virtual memory
More instructions in use can be stored in the fast to access RAM
What is RAM and it’s purpose
Random Access Memory
To store instructions currently in use
Properties of primary storage
and how its properties are different to secondary
Usually volatile
Faster to access
Lower capacity than secondary
What is virtual memory
Secondary storage used as primary storage
When is virtual memory used
When RAM is full but there still needs to be room for instructions in use to go
A con of virtual memory and why
It is slower than primary storage because it needs to send the data back to primary storage first
2 types of primary storage
RAM and ROM
What is ROM and what does it do
Read-Only Memory
Contains the bootstrap system (BIOS) which runs checks on the computer and tells the computer to transfer the operating system from secondary storage to RAM
What is firmware
A combination of hardware and software
Permanent software
Why is secondary storage needed
To store instructions not currently in use for long term
Differences between RAM and ROM
RAM is read and write
RAM is volatile
RAM is used in F-D-E cycle
Ram has higher storage
What is primary storage definition
Storage that CPU can quickly access
What is secondary storage definition
Storage that stores instructions currently not in use
What are the 3 types of secondary storage
Optical
Magnetic
Solid State
How does Magnetic drive work
Data is stored as magnetic charge on a spinning disc
How does SSD work
Electronically
How does optical data work
Pits and lands work as 0s and 1s
6 ways of measuring how good a memory type is
Capacity
Cost (per MB)
Portability
Reliability
Durability
Speed
What are advantages and disadvantages of magnetic storage
Advantages Disadvantages
Capacity Speed
Cost Reliability
What are advantages and disadvantages of solid state storage
Advantages Disadvantages
Capacity Cost
Speed Limited amount of read/writes
What are advantages and disadvantages of optical
Advantages Disadvantages
Cost Capacity
Durable Speed
State all of the measurements of data in ascending order
Bit
Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte
Petabyte
Why is data stored in binary
Because it is easier for electronics and the components
It is elegant as it is a simple on or off
How to workout the size of a text file
bits per character x number of characters
How to workout the size of a sound file
Sample rate x bit depth x duration
How to workout the size of an image
colour depth x image height x image length
105 in binary
01101001
10110101 in denary
181
187 in hexadecimal
BB
What does binary shift left do
Double the number
What is an overflow error
When adding binary and the number is more than 8-bits
How many bits does ASCII use
8
What is a character set
Collection of characters used to represent text in a computer system
How many characters can ASCII represent
256
How many bits does Unicode use
16
What are images made of pixels called
Bit-map
How to increase the colour depth of an image
Increase the amount of bits used to represent one pixel
What is metadata
Data providing information about one or more aspects of another data
How is sound converted to digital data
Analogue sound is picked up by microphone, analogue to digital converters convert the analogue sound into data, by sampling the sound at regular intervals
Why is compression needed
Reduce file size
What is lossy compression
Some unnecessary data is removed from the file
What is lossless compression
Data is temporarily removed from a file but when opening the file the computer is told how to return the file to it’s original state
Pros of lossy compression
Reduced size
Most data removed is unnoticeable
Often is necessary to use
Cons of lossy compression
Data is lost
Worse quality
Can’t return file to original
Pros of lossless compression
Can be used on text
No data lost
Can return to original
Cons of lossless compression
Not that big reduction in file size
When is lossy compression used
Image and sound files
When is lossless compression used
Text, (image and sound sometimes)
