System Architecture and Memory

System Architecture and Memory

1. CPU

   • Performance
     • Clock speed
       • No of cycles per second
       • Measured in Hertz (Hz)
     • No of cores
     • Cache size
   • Cache
     • Stores instructions from the CPU
     • 3x levels
       • Level 1
         • Fastest access
         • Smallest
       • Level 2
         • Slower
         • Bigger
       • Level 3
         • Slowest
         • Biggest
   • Fetch, decode, execute

2. Von Neumann

   • Control Unit
     • Controls flow of data
     • Decodes instructions
   • Arithmetic Logic Unit (ALU)
     • Carries out calculations and logical decisions within the CPU
   • Accumulator (ACC)
     • Stores results of ALU calculations
   • Logical internal structure
   • Data and programs both stored in the same place
   • Registers
     • Tiny amounts of high speed memory within the CPU
     • Each holds a specific piece of information
     • They hold the information needed for the CPU to work

3. Memory

   • Primary storage
     • Data currently in use
     • ROM
       • Read Only Memory
       • Can only read, cannot write to
       • Stores boot up instructions
       • Non volatile
     • RAM
       • Random Access Memory
       • Can read and write to
       • Volatile
       • Temporary data from running programs and files
       • Virtual memory
         • Special type of RAM
         • On the hard drive
         • Used when RAM is full
       • Flash memory
         • Special type of non volatile RAM
   • Secondary storage
     • Non volatile
     • Used to store files and programs
     • Magnetic
     • Solid state
     • Optical