Computing

Computing

1. Computing Hardware

   • CPU (Central Processing Unit): performs fetch execute cycles
   • RAM: stores data and programmes that are currently in use/ currently running
     • Volatile
   • ROM: loads operating system and is used to start up the computer
     • Non-volatile
   • Virtual Memory: a section of the hard drive used to store items in RAM which are not currently in use
   • Cache: high-speed memory that stores frequently used instructions
   • Input and Output Devices
     • Input
       • Keyboard
       • Mouse
       • Scanner
       • Barcode Reader
     • Output
       • Printer
       • Monitor
       • Speakers
     • Specific Needs
       • Braille Keyboard
       • Puff-suck switch
       • Braille Printer
   • Secondary Storage
     • Magnetic
       • Very large capacity/ very cheap
     • Optical
       • Cheap/ portable/ readable by most computers
     • Solid-State
       • Quick access/ not sensitive to being moved around

2. Flowcharts

   • Flowchart: a diagrammatic method of showing the structure and data flow to define a problem and its solution
   • Algorithm: a series of steps to work out a mathematical or other problem
   • Iteration: a group of instructions executed repeatedly until a condition is met

3. Representation of Data

   • Images
     • Resolution: the amount of pixels there are per unit
       • The higher the resolution, the bigger the size of the bitmap file
     • Metadata: information about an image that allows the computer to recreate it
   • Sound
     • Sampling Rate: how often the computer takes a measure of the sound
       • Bit Rate: how many bits are used for each sample
   • Character Sets
     • ASCII
       • 7 bit
     • Unicode
       • 16 bit
         • 65,536 characters

4. Databases

   • Data Types
     • Boolean
     • Real
     • Integer
     • Currency
     • Autonumber
   • Verification: Ensures that the data entered exactly matches its original source
   • Validation: An automatic check done by the computer to check that the data entered is reasonable – it doesn’t check accuracy
     • Length Check
     • Range Check
   • Entity: an object that exists in the real world
     • Table: holds information about an etity
   • DMBS (DataBase Management System): A program or collection of programs that enables you to store, modify, and extract information from a database
   • Forms, Reports and Queries
     • Forms: User- friendly way to enter data into a table
     • Query: A way of interrogating a database
     • Report: The output of a database
   • Primary Key: a piece of unique information
     • Foreign Key: link to a primary key in a parent table

5. Logic Gates

   • AND
   • NOT
   • OR

6. Programming

   • Selection: a pathway through the program is selected by using a condition
   • Sequence: a list of instructions executed in order, one after the other
   • A decimal number is called a float or in some cases a real

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