From hw

• What is embedded code in HTML?

  Code directly on a HTML page
• What is an example of embedded JavaScript code?

  <Scripts> Alert("hello world"); </script>
• What are all subroutines in JavaScript called?

  Functions
• What does the function say_hello do?

  It alerts "hello world"
• How is an event detected in JavaScript?

  Using a function with an HTML element
• What is the syntax to define a variable in JavaScript?

  Var age = 17;
• What is the syntax for a for loop in JavaScript?

  For (var i = 0; i < 5; i++)
• How do you define an array in JavaScript?

  Var colours = ["red", "orange", "yellow"];
• How do you add a color to an array in JavaScript?

  Using colours.push("green");
• What does the function multiply do?

  It returns the product of two numbers
• What is the syntax for an alert box in JavaScript?

  <script> Alert("hello") </script>
• How can you output a result directly onto a web page?

  Using document.write(result);
• How do you use tags to mark-up content in JavaScript?

  By using document.write("<h1>", result, "</h1>");
• How do you change the value of an HTML element in JavaScript?

  Using document.getElementById("example");
• What does the chosen_element variable represent?

  A reference to the HTML element with ID "example"
• What are the main components of a JavaScript function?

  • Function keyword
  • Function name
  • Parameters (optional)
  • Function body
  • Return statement (optional)
• What are the differences between a for loop and a while loop in JavaScript?

  For Loop:

  • Executes a block of code a specific number of times
  • Initialization, condition, and increment in one line

  
  

  While Loop:

  • Executes a block of code as long as a condition is true
  • Initialization is separate from the loop condition
• Operating systems allow the user to communicate with the computer and perform low level tasks
• operating systems provide the following features

  1. memory management
  2. resource management
  3. file management
  4. input / output management
  5. interrupt management
  6. utility software
  7. security
  8. user interface
• memory management is done by the processes:

  1. paging
  2. segmentation
  3. use of virtual memory
• paging is when memory is split up into equal sized sections called pages,

  pages can be swapped between main memory and the hard disk as and when needed.
• segmentation is splitting up memory into logical sized divisions, known as segments

  so this splits it up based on logical flow and structure os the program
• virtual memory used a section of the hard drive to act as RAM ,this is where the programs go that are not in use and are moved her by paging freeing up space
• what are issues of paging , segmentation and virtual memory?

  disk thrasing
• disk thrashing is when the computer freezes as the packets are being swapped too much between hard disk and main memory.
• interupts are signals generated by software or hardware to indicate to the processor that a process needs attention

  interrupts are stored in order of priority within a priority queue in the interrupt register.
• Abstraction is removing unnecessary information making it simple and easy for anyone to use
• Pros of abstraction:

  • Reduces development time
  • Simplifies problems
• selection/branching

  makes the program run blocks of code based on a condition
• bubble sort:

  • Not efficient for large data sets
  • Repetitive
  • Merge is more efficient for 250,000 bits of data in data base
• queue follows the FIFO pro pile and is for scheduling
• Stacks use the LIFO principle and act like an undo feature