System Architechture

System Architechture

1. cpu

   • fetch decode execute cycle
     • fetch
       • PC (program counter) creates an address. this is carried to MAR ( memory address register). the data in the data in that location is then placed on the data bus and carried to the MDR (memory data register)
     • decode
       • the data is decoded to find if its data or instructions to do something like add store repeat etc
     • execute
       • the cpu executes the instructions
   • clock speed
     • how fast the cpu can run. measured in MHz or GHz
   • cores
     • cpu's with multiple cores have more power
   • cache size
     • larger cache means shorter trips for electrical pulses so makes the computer faster

2. cache memory

   • L1
     • usually part of the cpu chip. L1 is the smallest but fastest to access chip
   • L2
     • bigger than L1 and is built between CPU and RAM. takes slightly longer to access
   • L3
     • bigger than L2

3. von neuman architecture