Unit 2 - Computer Science

Unit 2 - Computer Science

1. CPU

   • Purpose - Executes instructions from programs and manages hardware
   • Fetch-Execute Cycle
     • Fetches one instruction at a time
     • Fetches instruction from Main Memory
       • Decodes instruction
         • Execute instruction
   • Clock Speed
     • The rate at which the CPU processes data at
       • Faster Rate = Higher Performance
     • Measured in cycles per second or 1 hertz
   • Cache Size
     • Small chunk of fast memory
       • Stores most accessed data
     • Built within the CPU
     • CPU looks into the cache first to save time

2. Memory

   • RAM
     • Volatile Memory (Doesn't store data without power)
       • Can be easily written to and read from Can be altered easily
     • 'Copies' the operating system and applications
   • ROM
     • Non-Volatile Memory (Stores data without power)
       • Needed to remember instructions
       • Stores BIOS (Basic Input / Output System)
   • Virtual Memory
     • A portion of the hard drive that helps RAM to load applications
       • If an application or operation requires too much RAM, the computer selects virtual memory for use to compensate
   • Cache Memory
     • Memory stored in the CPU
     • CPU can access data from this much quicker than from the main memory
   • Flash Memory
     • Non-volatile memory
     • Commonly used storage medium

3. Binary

   • A numerical code primarily used by computers. Consists of 1's and 0's

4. Input and Output Devices

   • Allows the user to interact with the computer and visualise it
     • Allows computer-user functionality
   • Input Devices include keyboards, mice and web cameras
     • Takes in input from the user and interprets in the computer
   • Output Devices include monitors, speakers and printers
     • Takes data and materialises it into something the user can perceive and interpret
   • Some devices are specifically made to compensate for the user's disability