Standard Algorithms

Linear Search- This searches a list of numbers to find out which position a certain number is in the list.  It searches every number in the list until the number indicated is found.  After this is achieved the loop finishes and the number’s position is displayed.  

Example- if current-number = search-number then

position = current-item position

 

Count Occurrences- This standard algorithm searches a list of numbers one by one and counts how many times said number appears then outputs the result.  It uses a counter and every time the given number is found 1 is added to the counter.  

Example-  if current_number  =  occurrences_number then

 counter  =  counter + 1

 

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Implementation

equence, Selection and Iteration:

Sequence– Every line of code is executed in order from top to bottom.

Selection– The program can make decisions, using THEN…ELSE…IF

Iteration– Basically an up-market way to describe repeat.  It allows our program to do things over and over again.

The 7 Characteristics of a completed program:

  1. Correct – Ensures the completed program meets the software specification
  2. Maintainable – Means that you are able to alter it and correct bugs easily
  3. Reliable – Will always give the correct answer every time no matter what.  eg if it was asked 5+3 a million times it would output 8 a million times
  4. Readable – The program makes use of white spaces, utilizes internal commentary and also uses relevant names for variables
  5. Portable – Has the versatility to run on any type of computer
  6. Efficient – Doesn’t slow down the computers performance in anyway. eg. by using too much memory
  7. Robust – Will keep working no matter what is thrown at it

The 3 types of programming language:

  1. Procedural – Has an obvious start and end point and it’s sequence is specified by the programmer
  2. Declarative – At the beginning the programmer declares everything, queries can be used to solve problems
  3. Event-Driven – Permits the user to make the Human-Computer-Interface, things in the program are activated from the user pressing a button etc

High Level vs Low Level Language:

Programming languages that are generally written in English and use words such as IF, ELSE, REPEAT are known as High Level Languages, it is worth noting that computers do not actually understand this kind of language.  However computers do understand binary codes (machine codes), this is known as a Low Level Language.

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Entity Relationship Diagrams and Data Dictionaries

A Data Dictionary is a document which lists all of the fields of a database and stores things about them, such as validation, the amount of characters it requires and whether it is a primary or foreign key.

An Entity Relationship Diagram is a graphical representation of all the entities in a database which shows their relationships with each other.  There are three types of relationships entities can have, these are one to one, one to many and many to many.

 

 

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Pixlr Image Editing Tools

  • paintbrush – allows the user to colour in certain areas of their picture which they indicate with the cursor.  The paintbrush tool is the third down to the right on the pixlr toolbar.
  • fill – lets the user fill an entire picture with a particular colour, it is the tool directly below the paintbrush tool.
  • decrease resolution – allows the user to decrease the amount of pixels by width and height, it increases image quality but makes the image smaller.  This can be accessed via the image tab by selecting image size.
  • alter colour depth – changes the vibrance of colours in the image.  Can be accessed through the adjustment tab by selecting colour vibrance then moving any of the three sliders to change the colour depth.
  • crop- Lets the user select which area of the image they wish to save.  Accessed from the image tab and by selecting crop (the bottom option)
  • alter brightness and contrast- Changes how dark or bright the image is, if the brightness is set to maximum it makes the picture white, while if it is set to maximum  the image turns black.  This can be selected in the adjustment tab and by selecting the first option.
  • re-size or scale image- This can be performed by using the navigator slider to the right of the image.  It makes the image smaller or bigger but changes the quality accordingly.
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Bitmapped Graphics

I have learned that there are four main file formats which can be used to store a bitmapped graphics:

 

  • Bitmap (BMP)
  • Graphic Interchange Format (GIF)
  • Joint Pictures Expert Group (JPEG)
  • Portable Network Graphics (PNG)

I have also learned that bitmapped graphics can be compressed, this may reduce the image quality but it also reduces the image size which makes it easier for people to share their graphics through email etc.

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The Processor

Von Neumann Architecture

This is a design architecture for a computer processor; it’s subdivisions are Main memory, Output Devices, Input Devices and Backing Storage.

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A Control Bus is used for the computer to communicate with other devices within the computer; it is the idea that there are many shoe boxes with different addresses.

 

The Arithmetic Logic Unit (ALU) is a digital circuit which performs operations within the computer.

 

A Bus transfers data in a computer, there are many buses such as:

 

The Address Bus, carries information from the processor to main memory.

The Data Bus, information that is carried to and from the processor and main memory.

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Representing Real Numbers

When we use a real number, we do not store decimal points. As an alternative, we using floating point representation, this is when the decimal point is moved as far left as possible to leave us with a whole number, the mantissa. The number of spaces the decimal place has been moved is known as the exponent.

Example:

10011011 x2 0110 > (this would be above)

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