RISC

CISC

1. RISC stands for Reduced Instruction Set Computer.1. CISC stands for Complex Instruction Set Computer.
2. RISC processors have simple instructions taking about one clock cycle. The average clock cycle per instruction (CPI) is 1.52. CSIC processor has complex instructions that take up multiple clocks for execution. The average clock cycle per instruction (CPI) is in the range of 2 and 15.
3. Performance is optimized with more focus on software3. Performance is optimized with more focus on hardware.
4. It has no memory unit and uses separate hardware to implement instructions..4. It has a memory unit to implement complex instructions.
5. It has a hard-wired unit of programming.5. It has a microprogramming unit.
6. The instruction set is reduced i.e. it has only a few instructions in the instruction set. Many of these instructions are very primitive.6. The instruction set has a variety of different instructions that can be used for complex operations.
7. The instruction set has a variety of different instructions that can be used for complex operations.7. CISC has many different addressing modes and can thus be used to represent higher-level programming language statements more efficiently.
8. Complex addressing modes are synthesized using the software.8. CISC already supports complex addressing modes
9. Multiple register sets are present9. Only has a single register set
10. RISC processors are highly pipelined10. They are normally not pipelined or less pipelined
11. The complexity of RISC lies with the compiler that executes the program11. The complexity lies in the microprogram
12. Execution time is very less12. Execution time is very high
13. Code expansion can be a problem13. Code expansion is not a problem
14. The decoding of instructions is simple.14. Decoding of instructions is complex
15. It does not require external memory for calculations15. It requires external memory for calculations
16. The most common RISC microprocessors are Alpha, ARC, ARM, AVR, MIPS, PA-RISC, PIC, Power Architecture, and SPARC.16. Examples of CISC processors are the System/360, VAX, PDP-11, Motorola 68000 family, AMD, and Intel x86 CPUs.
17. RISC architecture is used in high-end applications such as video processing, telecommunications, and image processing.17. CISC architecture is used in low-end applications such as security systems, home automation, etc.