Computing Science

Computing Science

1. Graphics

   • Vector
     • Objects are placed on top of each other but remain seperate
     • Does not become pixelated if zoomed in
   • Bitmap
     • Overlapping objects removes what was underneath
     • Gives you pixelation when zoomed in

2. High-level machine code

   • Python

3. Low-level machine code

   • Binary
     • Maths within binary
       • Addition
       • Multiplication
       • Subtraction
       • Two's complement
       • Floating point representation
         • Real numbers are stored as floating point or scientific notation
         • Numbers stored as a mantissa, base and exponent
           • Mantissa
             • In a floating point number the mantissa holds the digits of a number
           • Base
             • The number of different digits which may be used at each place value, including 0. Base 2 has two digits; 1 and 2. Base 10 has ten digits; 0 through to 9.
           • Exponant
             • Part of a floating point number which contains the power to which the base must be raised
     • Advantages
       • Fewer rules are needed for only 2 digits
       • Small changes in voltages will not change data
       • Two states are easily identify presence or absence of data
     • Disadvantages
       • Very hard to find errors in as a large number of digits are required to represent numbers, texts and graphics
     • Computers work in binary
     • Two states (on and off)

4. Translators

   • Compiler
     • Runs fast
     • Reports mistakes at the end of compilation
     • Whole program is translated (compiled) at once
     • Translate and run are separate processes
     • Can save object code (translated version)
     • Compiler is not required to run code
   • Interpreter
     • Runs slow
     • Reports mistakes immediately
     • Are translated (interpreted) one line at a time
     • Translate and run is a single process
     • Connot save translated version
     • Interpreter is required to run the code

5. Computer architecture

   • Processor
     • Control Unit
       • Makes sure instructions are carried out in the correct order
     • Arithmetic Logic Unit (ALU)
       • Carries out the calculations (arithmetic)
       • Makes the decisions
         • When a computer makes decisions it's known as the Logical Operator
           • For example if the computer were to decide which number was bigger, that would be an example of a logical operator
     • Registers
       • Registers are a group of storage locations in the processor
         • Used to hold data being processed

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