computing 1.1

computing 1.1

1. embedded systems are computers built into other devices, larger ones, for example a washing machine. they are dedicated to one single task so they are efficient.

2. processor speed

   • measured in hertz(Hz)
   • typical speeds have spanned across MHz and GHz
   • 1 GHz processors executes 1 billion instructions per second, a 2 GHz processor executes 2 billion instructions per second

3. how common characteristics affect CPU performance

   • clock speed: the number of instructions a processor can carry out per second. higher clock speed = faster CPU
   • number of cores: the more cores a CPU has the more instructions it can carry out simultaneously, more cores = faster processing
   • cache size: increasing cache size will reduce the number of memory to disk transfers and thus may speed up processing of these instructions.

4. von neumann architecture

   • John Von Neumann designed computers with stored programs
   • a fixed program computer is a computer with 1 function and would have to be redesigned to change it.
   • stored program computers have changeable programs.

5. system buses

   • address bus
     • carries addresses from processor to main memory
     • it is in one direction(uni-directional)
   • data bus
     • carries data/instructions from main memory to the processor
     • bi-directional(two way)
     • data can be read/written
   • control bus
     • control signals are sent along the control bus

6. fetch-decode-execute cycle

   • fetch
     • program counter is incremented for each instruction of the program being executed
     • the contents of the program counter are put into the MAR
     • the address is transferred along the address bus to main memory
     • the data/instruction that has been addressed is transferred back to the processor along the data bus
     • this is held in the memory data register
     • the instruction would then be transferred to the current instruction register