CISC V RISC

• What are the two main categories of instruction sets in computers?

  Complex Instruction Set Computer (CISC) and Reduced Instruction Set Computer (RISC)
• What is the instruction set in a computer?

  It is the set of all instructions written in machine code that can be recognized and executed by a CPU.
• What is the purpose of the execution unit in a computer?

  • Carries out all calculations
  • Operates on data loaded into registers
• How would you store the product of two numbers in a computer's memory?

  The product should be stored back in memory location $0001$.
• What does the CISC architecture aim to do in terms of assembly code?

  CISC aims to complete tasks in as few lines of assembly code as possible.
• How does the complexity of CISC hardware compare to RISC hardware?

  CISC hardware tends to be more complicated than RISC hardware.
• What is an example of a complex instruction in CISC?

  The instruction for multiplying two numbers, referred to as 'malt'.
• What is a disadvantage of CISC instructions in terms of execution time?

  Complex instructions might take more than one machine or clock cycle to execute.
• Which architecture is mainly found in desktop computers and laptops?

  CISC architecture.
• What is the main goal of RISC processors?

  To use simple instructions that can be executed within a single machine or clock cycle.
• How many lines of assembly code are needed to perform a multiplication in RISC compared to CISC?

  Four lines of assembly code are needed in RISC compared to one line in CISC.
• What is a consequence of RISC requiring more lines of code?

  More RAM is needed to store the assembly instructions.
• What advantage does RISC architecture provide in terms of instruction execution time?

  Each instruction can be completed in a single clock cycle.
• Why are RISC architectures popular in low power and portable devices?

  They have lower energy requirements and simpler hardware.
• What are the key differences between CISC and RISC architectures?

  CISC:

  • Complex instructions
  • Fewer lines of assembly code
  • More complicated hardware
  • May take multiple clock cycles

  
  

  RISC:

  • Simple instructions
  • More lines of assembly code
  • Simpler hardware
  • Each instruction completes in a single clock cycle
• What is the performance equation in relation to CISC and RISC?

  CISC minimizes the number of instructions per program while sacrificing cycles per instruction, whereas RISC reduces cycles per instruction at the cost of more instructions.
• What is a challenge associated with CISC instructions when utilizing pipelining?

  The variable length of CISC instructions can be problematic for pipelining.
• Why did RISC take a long time to gain acceptance in the market?

  RISC lacked software support compared to CISC, especially in the early days.
• How did Intel's influence affect the emergence of RISC architecture?

  Intel's powerful CISC processors hindered the acceptance of RISC as an emerging technology.
• What has contributed to the rise of RISC-based processors in recent years?

  The reduction in price of RAM and increased sophistication of compiler technology.