CS

• What is abstraction?


  Foccusing on just the important details of a problem
• Decomposition

  Breaking a problem down into smaller parts so that it is easier to solve
• Algorithmic thinking


  creating a step by step solution to a problem
• Linear Search


  Checks each item in the list one by one until it finds what it is looking for

  +Simple,list doesn't need to be ordered

  -Not efficent,takes time with lots of data
• Binary Search


  Finds the middle item in an ordered list by doing(n+1)/2.If the middle item is what is is searching for it stops.If not,it compares the itme you are seraching for to the middle item so that is knows whethere to look in the first half or second half of the list.Then it repeats these steps until item is found.

  +More efficent than a linear search

  -Only works on an ordered lsit ,complest to program
• Sorting algorithms 


  sort times into an ordered list
• Bubble sort


  Checks the first two items in a list swaps them if they are in the wrong order and then moves onto the next two items and repeats the process.Once it has passed through the list once it goes through again until none of the items need swapping.

  +Simple

  -Takes a long time
• Merge sort


  Finds the middle item (n+1)/2 and splits the list in half.Repeats this step until the list is split into individual items(sub-lists).It then merges(joins) the sublists in pairs.Each time the sublists are paired they are sorted into the correct order.

  +Efficient

  -Slow
• Insertion sort


  Looks at the second item in a list and compares it ot the items that are infront of it ,then inserts it into the right place.It then moves to the next item in the list and repeats these steps.

  +Quick for sorting small lists

  -slow with long lists
• Logic and trace tables

  NOT GATES

  Fill in the word

  A) opposite

  
• AND GATE

  Fill in the words

  A) 1

  B) inputs

  
• COMBINED GATES

  Fill in the word

  A) combined

  
• What are character sets in computing?

  Characters recognized by a computer system
• How is each character represented in ASCII?

  By a 7-bit number with a leading 0
• What does Extended ASCII use to represent characters?

  8-bit binary numbers
• How many possibilities does Extended ASCII provide?

  256 different possibilities
• What does Unicode allow for in character representation?

  Characters from all languages
• How many bits does Unicode use for each letter?

  16-bit or 32-bit binary number
• What are images made up of?

  Pixels
• How is the color of each pixel represented?

  By a binary number
• What happens if an image uses 1 bit for color representation?

  It can only display 2 colors
• What does increasing the number of bits for color representation do?

  Allows for more color options
• What is color depth?

  Number of bits used for each pixel
• How is resolution measured?

  In dots per inch
• What happens to file size with higher resolution or color depth?

  File size increases
• What is metadata in an image file?

  Information about the image file
• What is the nature of sound when recorded?

  It is an analogue signal
• Why must sound be converted to a digital signal?

  To store it on a computer
• What is sampling in sound recording?

  Measuring the amplitude at intervals
• What is the effect of more frequent sampling?

  Creates a more accurate sound file
• How does the analogue wave differ from digital sampling?

  Analogue is smoother and continuous
• What is the purpose of compression?

  To make file sizes smaller
• What is lossy compression?

  Permanently removes some data
• What is lossless compression?

  Data is temporarily removed and restored
• What are the key concepts of computer systems?

  • Data input, processing, and output
  • Embedded systems for single tasks
  • Clock speed affects CPU speed
  • More cores enable multitasking
  • Larger cache improves data access speed
• What does the CPU do in the fetch-decode-execute cycle?

  Fetches, decodes, and executes instructions
• What does the Control Unit (CU) do?

  Executes instructions and controls data flow
• What does the Program Counter do?

  Holds the memory address for instructions
• What is the function of the Arithmetic Logic Unit (ALU)?

  Performs calculations and logic operations
• What does the Accumulator do?

  Holds results of calculations in ALU