Computer Science Cards

What is meant by Hertz (Hz)?

The SI (International system of units) unit of frequency defined as the number of cycles per second of a periodic phenomenon.

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What is sampling rate?

The number of samples taken per second.

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Why is it difficult to save analogue sound waves in a digital format?

Analogue is continuous data, converting continuous data to discrete values may loose some of the accuracy.

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Name a perpheral that could be used to feed sound into an ADC (Analogue to digital converter).

A microphone.

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What is the difference between analogue and digital data?

Analogue data is continuous, allowing for an infinite number of possible values. Digital data is discrete, allowing for a finite set of values.

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What is the role of an ADC (analogue to digital converter)?

Converts analogue sound into digital signals that can be stored on a computer.

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What is an advantage of Bitmapped images rather than Vector graphics?

Advantage of a bitmapped graphic is that if the image includes continuous areas of colour - the image will store less memory as bitmapped than if it is stored as a vector graphic.

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What are the factors that define a well-defined problem?

- Clearly defined goal - what you want to achieve. - Clearly defined given - the initial solution. - Resources - what is given to you to solve the problem. - Ownership - who is going to solve the problem.

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What are the advantages & disadvantages of First generation programming languages ?

Advantages - it is only language a computer can actually understand. All other languages must be translated into machine code to run. Disadvantage - It's pretty much impossible for humans to read.

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what is meant by First Generation programming languages & what are some basic operators in FGL.

Machine code is the actual sequence of 0's and 1's that a computer can directly decode and run. Basic Operators - Add, Store and Load.

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Second generation programming languages an improvement of FGL. What are the disadvantages of SGL's

- Uses simple letter abbreviations to make machine code easier to remember, read and write. Advantages: Simpler for humans to understand. A simple one-to-one translation of machine code instructions allows direct manipulation of computer.

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What are the disadvantages of Second Generation Programming Languages?

Needs to be translated (Assembled) in order to run. This isn't difficult, but it's an extra step. This is because it's a one-to-one transition of machine code, it's very long-winded and machine rather than problem focused.

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What is a vector graphic & in relation to that what is a drawing list?

Vector graphic: images defined using mathematics and Geometry such as points, lines, curves and shapes or polygons. Allowing for scalability. Objects and properties stored mathematically. Drawing list: a set of commands used to define a vector image.

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What are the advantages of vector graphics rather than Bitmap graphics?

-They are not distorted when they are scaled because they are intrinsically resolution free. - If the image involves a shape, it will store less memory that if it is stored as a bitmap. - They are distorted when they are scaled.

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If you wanted to record a 30 second voice nore on your mobile phone you would use the following: Sample Rate = 8,000 Hz, Sample Resolution = 16 Bit, Length of sound = 30 Second, How would you work out the file size?

8000*16*30 = 3840000 Bits, 480,000 Bytes. //Answer not compulsory just correct use of formula

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Why might a digital representation of a sound struggle to be a perfect representation?

A sound wave is continuous data, whilst data is discrete and the representation is an approximation of the original.

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Why might you choose to have a lower sampling rate than a higher one for storing a song on your computer?

The higher the sampling rate, the more data is needed to be stored, meaning the larger the file size.

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Why might you prefer to use sound synthesis (MIDI) over recording an orchestra?

Sound synthesis produces smaller file sizes without loss of quality.

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Computers are made up of hardware and software. Define what is meant by these two terms.

Hardware: Physical components that make up a computer. Software: Sequences of instructions or programs which run on the computer.

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what is the definition of bit rate and how would you work out size of a sound sample?

Bit rate - the number of bits to store 1 second of sound. Formula: File Size = Sample rate * Sample resolution * Length of sound or File Size = Bit rate * Length of sound.

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fourth generation, known as declarative languages give an example of a 4gl. An advantage & a disadvantage. ensure you mention translators.

4th generation programming languages such as Prolog and SQL. Are instructions that define what is to be done, but not the detail of how to do it. Advantage - they simplify complex tasks. Disadvantage: not suitable for all problems. uses Comp & Interp

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Machine code instructions are a single number that has two parts, name them and explain there purpose.

An operator (Op-Code) tells the computer what to do (e.g. Load, Store), the operand (Second part of instruction, e.g. #60) tells the computer what to do with the instruction.

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Define Nyquist's theorem.

Nyquist's theorem - the sample rate should be at a frequency which is at least twice the value of the highest frequency in the sampled signal

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Name the device used by computers to convert sound files into sound coming out of the speaker.

Digital To Analogue Converter (DAC)

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Computer Science Cards

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Other cards in this set

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Card 5

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