1.1 - Systems Architecture: Computer Science - Incomplete

• CPU stands for Central Processing Unit
• CPU is a hardware component that controls the manipulation and processing of data
• There can be several processors in a computer, including multi-core CPUs
• Processors are used interchangeably with CPUs, but can also refer to graphics cards and sound cards
• CPU components:

  • ALU (Arithmetic Logic Unit): carries out instructions, performs operations like addition, multiplication, division, and logic operations
  • Control Unit: coordinates the CPU, oversees processing, decodes instructions, and manages data transfer
  • Registers: small, quick storage units on the CPU used for efficiency and temporary storage during operations
• Von Neumann architecture:

  • Modern computers follow this architecture
  • Main components include memory, control unit, processing unit, and input devices
  • Instructions and data are stored together in memory
  • Stored program concept: instructions and data stored together in memory in binary form
• Clock:

  • System clock provides timing signals for synchronization
  • Used by circuits to synchronize operations
  • CPU operates at a specific frequency determined by the clock speed
  • Clock speed is crucial for CPU performance, measured in clock cycles per instruction
• Fetch-Execute Cycle:

  • Fetch: CPU retrieves instructions from memory
  • Decode: instructions are broken down into operator and operand
  • Execute: CPU performs the instruction using the ALU and control unit
  • Results are stored in registers or memory
• CPU has two categories of registers: special purpose registers and general purpose registers
• Special purpose registers are used for specific functions related to the history of the CPU
• General purpose registers are used by programmers to temporarily hold and manipulate data
• Program Counter (PC):

  • Holds the address of the next instruction to be executed
  • Increments after each fetch stage, usually by one
  • If it's a branching instruction, the PC will jump to a completely different address
• Accumulator (ACC):

  • Holds the result of a calculation before it's sent to main memory
  • Faster to store results on the chip rather than in main memory
• Memory Address Register (MAR) and Memory Data Register (MDR) are linked:

  • MAR holds the memory address that needs to be accessed
  • MDR holds the actual data being transferred to or from the memory location
  • MAR and MDR work together to read from or write to memory
• Special purpose registers act as buffers to compensate for speed differences between the CPU and main memory:

  • They exist to allow the CPU to continue with other tasks while data is being accessed from or written to memory
  • They help improve efficiency by allowing the CPU to work on other tasks while waiting for memory operations to complete