Chapter 10 Computer Systems

Chapter 10 Computer Systems

1. CPU - Central Processing Unit

   • Carries out instructions given to it. Inside of a processor there are billions of transistors which can be used to build the logic gates which can in turn be used to build the circuitry within the processor.
   • Processors run at incredible speeds in the modern era, the speed at which they run is called the clock speed. Measured in Gigahertz - 1,000,000,000 pulses a second
   • Inside the processor
     • Registers
       • Program Counters (PC)
         • Keeps track of the memory location of the line of machine code being executed.
       • Memory data register (MDR)
         • Stores the data that has been fetched from or stored in memory
       • Memory Address Register (MAR)
         • Stores the address of the data or instructions that are to be fetched from or sent to
       • Current instruction register (CIR)
         • Stores the most recently fetched instruction, waiting to be decoded and executed
       • Accumulator (ACC)
         • Stores the result of calculations made by the ALU
       • Arithmetic Logic unit (ALU)
         • The arithmetic logic uni,or ALU, carries out the calculations and logical decsions. The results of its calculations are stores in the accumulator
   • It works by fetching, decoding and executing instructions