Exam code: 1CP2
The ASCII system is used to represent letters and symbols.
(i) State the number of bits used to represent each letter or symbol in ASCII.
[1]
(ii) The ASCII code 65 represents the letter A.
Give the letter represented by the ASCII code 68.
[2]
Sound waves are converted to binary using sample intervals.
Define the term ‘sample interval’.
Give an expression to calculate the size of a bitmap image, not the size of the file that stores the image.
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Here is an original image.
There is one bit available to represent each pixel.
Explain one reason why the image cannot be accurately represented using one bit for each pixel.
An analogue sound is represented in digital form.
The sound is one second long and is sampled at 10Hz.
The digital representation has a bit depth of 5 and is stored in two’s complement.
Sound data:
0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1
Draw a graph to represent the data sampled.
You must include:
labels for the x and y axes
values for the x and y axes
each sample plotted as an format('truetype')%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ctext%20font-family%3D%22math13b8a614226a953a8cd9526fca6%22%20font-size%3D%2216%22%20text-anchor%3D%22middle%22%20x%3D%228.5%22%20y%3D%2216%22%3E%26%23xD7%3B%3C%2Ftext%3E%3C%2Fsvg%3E){kind=small}
samples joined up to show the digital form.
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Data can be encoded using ASCII.
Describe ASCII.
A pixel is the smallest element in a bitmap image.
Two images are displayed on the same screen.
One image is 1280720 pixels. The second image is 19201080 pixels.
The second image has a higher resolution.
State one reason why the second image will be displayed in more detail.
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