Category Archives: 6. External Sites

2. Software Development, Computing Higher, Homework

Homework for Wed 7th Dec

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  1. Give two reasons why computers use binary numbers to represent and store data.(2)
  2. Represent 0111 0100 in decimal.(1)
  3. Describe how graphics are stored using a bit-mapped package.(2)
  4. An image is 4 x 6 inches, has a resolution of 800 dpi and each pixel can display 65,536 different colours. Calculate the storage requirements of this image. Express your answer using suitable units. Show all working. (3)
  5. State two advantages of storing the above image as a vector graphic rather than a bit-map.(2)
  6. Represent 13.25 in floating point notation.  Express the mantissa in 16-bits and the exponent in 8-bits.(2)
  7. What is meant by the term lossless compression?(1)
  8. Explain how the Unicode system overcomes the limitations of ASCII.(1)
  9. How many different colours could be represented with a bit depth of one byte(1)

Out of 15.

Computing Higher

Prelim Preperation

The class will have a class assessment on the  16th of December, this assessment will cover all areas of the class covered.

The assessment will be based on a single past paper taken from the last 6 or so years, I will remove all the content we have not covered.

I will return the paper to you before the holidays so that you can look over the sections to need to study before the prelim.

2. Software Development, Computing Higher, Homework

NAB Preparation Task

Right, you should have finished off the prep task for next Tuesday Dec 6th.

The submission must have the following parts

  • Your pseudocode design
  • An implemented program matching your design
  • Indication of data flow at the top level of the algorithm
  • A test run showing the data from the task sheet

No time will be given in class to print it off, if you need to print it then do so at lunch time this week or on Monday.

1. Computer Systems, 3. Multimedia

Image sizes

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There are plenty of posts on the internet about image file sizes and image file types.

We discussed in class how to calculate image file sizes, however, it’s often hard for raw numbers to mean anything. We forget that file storage was not always the multi Gigabyte size it is now. Here is a way for you to try and get your head around it.

The new iPhone 4s’ camera has a resolution of 3264 by 2448 pixels @ 24 bits per pixel, how many uncompressed images can you fit on a standard 16GB iPhone 4s?

1. Computer Systems

Homework for Thursday 1st Dec

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Answer the following questions.

Convert the following to decimal

  1. 11111100 (2’s comp)
  2. 00110110
  3. 11111111 (2’s comp)

How many pixels in the following files

  1. 320×240 @ 8 bits/pixel
  2. 1024×768 @ 16 bit colour depth
  3. 1280×1024 @ 24bpp

What are the sizes of the following files in bytes

  1. 320×240 @ 8 bits/pixel
  2. 1024×768 @ 16 bit colour depth
  3. 1280×1024 @ 24bpp

Calculate the storage requirements for the following images in Megabytes (to 2 decimal places)

  1. 1440×1080 @ 24 bpp
  2. 1920×1080 @ 24 bpp
  3. 7689×4320 @ 24 bpp
1. Computer Systems

Data representation – Arrangements

  • Representation of positive numbers in binary including place values and range up to and including 32 bits
  • Conversion from binary to decimal and vice versa
  • Description of the representation of negative numbers using two’s complement using examples of up to 8 bit numbers
  • Description of the relationship between the number of bits assigned to the mantissa/exponent and the range and precision of floating point numbers
  • Conversion to and from bit, byte, Kilobyte, Megabyte, Gigabyte, Terabyte. (Kb, Mb, Gb, Tb)
  • Description of Unicode and its advantages over ASCII
  • Description of the bit map method of graphic representation using examples of colour/greyscale bit maps
  • Description of the relationship of bit depth to the number of colours using examples up to and including 24 bit depth (true colour)
  • Description of the vector graphics method of graphic representation
  • Description of the relative advantages and disadvantages of bit mapped and vector graphics
  • Description of the relationship between the bit depth and file size
  • Explanation of the need for data compression using the storage of bit-map graphic files, as examples