1.1 Systems Architecture

• CPU


  Central Processing Unit
• CPU


  • Processes instructions and data that make the system work
• Inside the CPU


  • Performs math and logic calculations
• Components inside the CPU

  • Arithmetic Logic Unit (ALU)-perform logic operations and, or, not
  • Control Unit (CU) coordinates the FDE cycle
• Cache


  Fast, small memory that holds frequently used data
• Registers


  • Memory Address Register (MAR)-stores the address where data/instruction will be fetched
  • Memory Data Register (MDR)-stores the instruction/data that has been fetched
  • Program Counter-stores the address of the next instruction to be executed
  • Accumulator-stores the results of arithmetic calculations
• Von Neumann architecture


  System where the CPU runs programs stored in memory
• FDE cycle


  1. Fetch-instruction is fetched from memory using the address in program counter

  2. Decode-instruction in the MDR is decoded by the CU

  3. Execute-instruction is performed/carried out, additional data is fetched
• CPU characteristics


  • Clock Speed - controls how many FDE cycles can be processed per second (Hz)
  • Number of Cores - each core can execute one instruction at the same time
  • Cache size - larger cache holds more regularly used items, faster than RAM
• Overclocking


  Making CPUs run at a higher clock speed than the factory-set rate, can cause overheating and damage
• Embedded systems


  Computers built into other devices, dedicated to a single task, more efficient than general purpose computers
• RAM


  Random Access Memory, used as the main memory in a computer, volatile memory that requires power to retain data
• ROM


  Read Only Memory, non-volatile permanent memory that can only be read
• Virtual memory


  Secondary storage used as extra RAM
• Hardware


  • CPU, motherboard, monitor, printer
• Software


  • Operating system, programs, applications