CISC and RISC

• What does CISC stand for?


  Complex Instruction Set Computer
• What does RISC stand for?


  Reduced Instruction Set Computer
• What are the main differences between CISC and RISC architectures?


  • CISC:
  • Complex instructions performing multiple operations
  • Aims to reduce the number of instructions per program
  • RISC:
  • Simple instructions executed quickly
  • Aims to execute one instruction per clock cycle
• What is the primary goal of RISC architecture?


  To execute one instruction per clock cycle
• How does a CISC processor handle multiplication compared to a RISC processor?


  A CISC processor uses a single instruction, while a RISC processor breaks it into separate load, multiply, and store instructions
• What are the key characteristics of CISC architecture?


  • Complex instructions that can perform multiple operations
  • Variable execution time depending on instruction complexity
  • Can access memory as part of many instructions
  • Fewer instructions in programs due to complex instructions
  • Typically fewer registers
• What are the key characteristics of RISC architecture?


  • Simple instructions that typically perform one operation
  • Aims for one instruction per clock cycle
  • Uses load/store architecture for memory access
  • More instructions in programs, but each is simpler
  • Typically more registers
• What is a disadvantage of CISC architecture related to hardware?


  It requires more transistors for instruction decoding
• What is a disadvantage of RISC architecture regarding code size?


  It can lead to larger code size due to more instructions needed
• What are the advantages of CISC architecture?


  • Efficient code density
  • Backward compatibility
  • Simpler compiler design
• What are the disadvantages of CISC architecture?


  • Complex hardware
  • Variable instruction execution time
  • Higher power consumption
• What are the advantages of RISC architecture?


  • Faster execution
  • Efficient pipelining
  • Lower power consumption
• What are the disadvantages of RISC architecture?


  • Larger code size
  • More complex compiler
  • Less efficient for complex operations
• In which scenario would RISC architecture likely be more beneficial?


  In scenarios requiring fast execution and low power consumption
• How does the instruction execution time differ between CISC and RISC architectures?


  CISC has variable execution time, while RISC aims for one instruction per clock cycle
• What is the impact of instruction complexity on the number of instructions in CISC and RISC architectures?


  CISC has fewer instructions due to complex instructions, while RISC has more instructions due to simpler ones
• What is one advantage of RISC architecture regarding instruction execution?


  Instructions can be executed in one clock cycle.
• How does uniform instruction length benefit RISC architecture?


  It allows for better pipelining.
• What is a key benefit of RISC architecture in terms of power consumption?


  Simpler circuitry requires less power.
• What is a disadvantage of RISC architecture related to code size?


  It has a larger code size.
• Why is the compiler more complex in RISC architecture?


  Because it needs to optimize instruction usage.
• How does RISC architecture perform with complex operations compared to CISC?


  RISC may require multiple instructions for tasks that CISC can do in one.
• In what scenario would a RISC processor be more beneficial than a CISC processor?


  A battery-powered mobile device requiring fast, simple calculations.
• What is a key advantage of CISC architecture regarding backward compatibility?


  CISC maintains complex instruction sets that can execute older software without modification.
• Name a common example of a CISC processor.


  x86 family.
• What is an example of a 64-bit extension of the x86 architecture?


  x86-64.
• Which RISC processor is dominant in mobile devices?


  ARM.
• What is a notable feature of RISC-V architecture?


  It is an open-source ISA gaining popularity.
• Name a processor that uses the MIPS architecture.


  PlayStation 2.
• What is a hybrid approach in modern processors?

  It translates CISC instructions into RISC-like micro-operations internally.
• What is an example of a specialized processor used for AI?


  Google's Tensor Processing Units (TPUs).
• What trend is observed with ARM-based processors?


  They are expanding beyond mobile devices into laptops and servers.
• What is a current trend in processor architecture regarding power efficiency?


  There is an increasing focus on energy efficiency in all processor designs.
• How do multi-core designs benefit both CISC and RISC architectures?


  They improve performance by allowing multiple instructions to be processed simultaneously.
• What is the significance of RISC-V in current trends?


  It is gaining popularity in various sectors due to its open-source nature.
• How do hybrid designs in modern processors affect performance?

  They allow for the advantages of both CISC and RISC architectures to be utilized.
• What are the advantages and disadvantages of RISC architecture?


  Advantages:

  • Instructions can be executed in one clock cycle.
  • Efficient pipelining due to uniform instruction length.
  • Lower power consumption from simpler circuitry.

  
  

  Disadvantages:

  • Larger code size requiring more instructions.
  • More complex compiler needed for optimization.
  • Less efficient for complex operations compared to CISC.
• What are the advantages and disadvantages of CISC architecture?


  Advantages:

  • Better backward compatibility with older software.
  • Smaller code size due to complex instructions.

  
  

  Disadvantages:

  • More power consumption due to complex circuitry.
  • Slower execution for simple instructions compared to RISC.
• What are the current trends in processor architecture?

  • Hybrid designs blending CISC and RISC approaches.
  • RISC architectures expanding into new markets.
  • Growth of open-source RISC-V architecture.
  • Specialized processors for AI and machine learning.
  • Focus on multi-core designs for improved performance.
  • Increasing emphasis on power efficiency.