Paper 2 Flashcards
What is natural numbers and its symbol?
All positive numbers whole numbers (integers) including zero
Symbol: N
What is integer numbers and its symbol?
All whole numbers including negatives and zero
Symbol: Z
What is rational numbers and its symbol?
Numbers that can be expressed as fractions
Symbol: Q
What is irrational numbers?
Numbers that cannot be expressed as a fraction
What is real numbers and its symbol?
Any number that isn’t infinity or imaginary
Symbol: R
What is ordinal numbers?
Numbers that can describe the position of an object
Why is hexadecimal used?
- Easy to represent a byte with two digits
- Easier for humans to remember
What is Unsigned and signed binary?
Signed binary - Binary values that can store both positive and negative values
(We use two’s compliment to represent this)
Unsigned binary - Binary values that can only store positive values
What are the advantages and disadvantages of fixed point(Signed Binary) and floating point(2s Complement) forms in terms of range, precision and speed of calculation?
Fixed point
+Allows for much faster processing compared to floating point numbers as no processing is required to move the binary point
+The absolute error will always remain the same, unlike floating point numbers
Floating point
+Wider range of numbers can be produced with the same number of bits as the floating point system
+
Why is floating point numbers normalised?
Allows the maximum possible precision with a given number of bits
Explain underflow and overflow and describe the circumstances in which they occur.
Overflow - When the number is too large for the number of bits allocated
Underflow - When the number is too small for the number of bits allocated
How does bit patterns represent sound?
This can be done by measuring and recording the amplitude of the sound wave, using a microphone, at given intervals. The more frequent the samples are taken, the more accurate the sound will be presented.
What’s the difference between analogue and digital?
Involving data and signals
Analogue data - Data that is infinitely variable and are often represented in the form of a wave
Digital data - Represented as discrete values
Describe the principles of an analogue to digital converter (ADC)
A microphone converts the sound energy to electrical energy. Regular samples are taken of the analogue signal at a given frequency, measuring the amplitude of the wave at each point and converting it into binary value according to the resolution or bit depth.
Explain how bitmaps are represented.*
An image made up of individual pixels, arranged as a grid
What is resolution for images?**
The number of pixels per inch
What is colour depth?
The number of bits needed to stored each pixel
Advantages of normalised floating point format over fixed point format?
- To allow a wider range of values to be stored
- To minimise rounding errors
- Greater accuracy
What is metadata and what data might it contain?
Extra information about an image.
- Dimensions (h*w/ radius ect)
- Colour depth
- file type
- Gps coordinates
- Time and date of photo taken
What is the formula for pixel resolution?
resolution = height (in pixels) * width (in pixels)
What is Nyquist theorem?
In order to produce an accurate recording, the sampling rate must be at least doubled that of the highest frequency in the original signal.
The average human can hear frequencies up to 20,000Hz
What is MIDI and a event messages and how is it represented?
A protocol that allows electronic instruments and other digital musical tools to communicate with each other.
Event messages specifies the pitch and duration of a note
MIDI represents sound as sequence of event messages // MIDI stores properties of the
notes played;
Advantages of using MIDI files for representing music over digital audio formats?
-MIDI files tend to be much smaller, therefore requiring less memory which leads to faster load times
-Completely editable
-Can support a wide range of instruments
Can produce very high quality reproduction of the instruments
What is the formula for the file size of sound?
Sample rate x Resolution x seconds
What is the formula for the file size of a bitmap image?
Number of pixels * colour depth
How to calculate the range of a given number of bits of 2^8?
find the biggest number and range of values you can have
2^8 = 256 values as you can also represent 0 2^8 = 255 is the biggest number that you can represent
Describe the principles of an digital to analogue converter (DAC)
- convert binary into electrical energy
- that then vibrates the speaker
- that creates pressure waves which are the analogue sound
What is sampling rate?
Represents the number of samples that will be taken per second
What is sample resolution?
The number of bits allocated to representing the sound
Explain why both fixed point and floating point representation of decimal numbers may be inaccurate?
They both have rounding errors
What base is decimal, binary and hexadecimal?
Decimal - 10
Binary - 2
Hexadecimal - 16
Describe sampled sound:
- Sampled sound records measurements of the amplitude of a wave
- Samples are taken at regular intervals
- Each sample is stored in a fixed amount of memory
How is sampled sound represented?
Sampled sound records measurements of (the amplitude) of a wave;
Samples are taken at regular intervals;
Each sample is stored in a fixed amount of memory; A. each sample is the same size
What are the two types of classification software?
System Software, Application Software
What are the 4 types of System software?
Operating System, Utility Programs, Library Programs, Programming Translators
What are the 3 types of Application Software?
Bespoke Software- made for a custom tasks
Generic off the shelf software-Designed to complete a broad range of tasks
Special Purpose (ready made)-Made for one particular task
What are operating systems and what is the function of it?
A program that designed to hide the complexities of hardware from the user.
Manages the operations of the computer for the user, acts as a bridge between the user and computers hardware.
Eg. Windows, MacOS, iOS
Function
- Moving data into and out of Ram
- Allocate I/O devices to processes
- Decides which process to carry out
- Disk fragmentation
Allocate processors/cores to processes // schedule processes // decide which process to
carry out when;
Allocate memory/RAM to processes // moving data into and out of RAM / to a paging file
for virtual memory // ensuring processes can only write to memory that they have been
allocated;
Allocate I/O devices to processes // manages communication between processes and I/O
devices // automatic installation of drivers for new I/O devices; A. examples of devices
NE. manages I/O devices
Allocate space on a storage device to files // organising files into directories // determines
where on a device to save a file // recognising storage devices when they are connected;
A. defragmentation of disks NE. saving a file
Installation of new software // automatic/managing updating of software;
A. “programs” or “tasks” for “processes”
R. handling interrupts
R. hides complexity
Note: Students must describe the type of resource management – phrases such as
“processor management”, “allocating memory” etc are not enough.
Define Software and Hardware?
Hardware is all the physical components that make up a computer
Software is the programs that run on a computer
What are Utility programs and examples of it?
Small programs with one specific purpose that is designed to optimise the performance of the computer.
- Disk Defragmenter
- Virus Checker
- Backing up files
- compressing or decompressing data
- encrypting data
- providing a firewall
What are library programs and examples of it?
Ready compiled programs which can be run when needed.
-Maths calculations
What are programming translators and examples of it?
Converts program code by a programmer into machine code which can be run by the computer
-Compilers, Interpreter, Assembly
What is System Software?
- Software that is needed to run the computers hardware and application programs
- Software that performs tasks to run computer;
- Layer of software which enables user to operate computer;
- Software that hides complexity of computer from user/provides virtual machine;
- Software that lets user communicate with/manage hardware;
- Software to run applications/hardware/programs/computer/ packages;
- Software required to make computer work;-
What is Application Software?
Software that carries out tasks that the user is interested in doing such as writing a letter, creating graphs, sending an email or downloading a webpage.
Performs tasks for the user
How does a operating system manages memory management?
It manages how much RAM a program has access to which allows multiple applications to run simultaneously.
How does a operating system manages processor scheduling?
Involves deciding what order to execute each instruction in. Only executes one instruction at a time
How does a operating system manages peripherals?
The OS uses device drivers to communicate with I/O devices connected to the computer system.
What is 1st generation language and its level?
(Low Level)
Machine Code - A line of code (1’s & 0’s) split into opcode and operand
What is 2nd generation language and its level?
(Low Level)
Assembly Language - The opcode is mnemonics and the operand is decimal/ hexadecimal
What is 3rd and 4th generation language and its level?
(Both High Level)
High level language - E.g. C#, Java etc
Declarative Language - You state what you want, not how to do it
What are the advantages and disadvantages of high level languages compared to a low level language?
+Relatively easy to learn
+Easier and quicker to write in high level language
+Capable of running on multiple different computers
-Requires a compiler to run
What are the 3 different types of programming translators?
Compiler, Interpreter, Assembler
What is the difference between a compiler and an interpreter?
- A compiler produces object code whilst an interpreter does not
- A compiler translates the whole of the source code into object code whilst an interpreter translates line by line
-The object code produced by a compiler will execute faster, (once it is compiled) than
interpreting the source code (every time the program is run)
-An interpreter can run (syntactically correct) parts of a program whilst there are
syntax errors in other parts of it, which a compiler cannot;
What is inputted into a compiler and assembler and outputted?
Source code goes in; object code comes out
