Explanation:
The CISC (Complex Instruction Set Computing) and RISC (Reduced Instruction Set Computing) architectures are two types of computer processor architectures. Both have been developed to reduce the semantic gap between high-level programming languages and the low-level machine language instructions that computers understand. However, the main difference between the two architectures lies in the approach they take to achieve this goal.

CISC Architecture:
The CISC architecture is an older architecture that was developed in the 1970s. It is characterized by a large number of complex instructions that can perform multiple operations in a single instruction. This architecture is designed to reduce the number of instructions required to perform a particular task, making it more efficient than earlier architectures.

However, the downside of the CISC architecture is that the large number of complex instructions can make the processor slower and more complex, leading to higher costs and longer development times. In addition, the complexity of the instructions makes it more difficult to optimize the processor for specific applications.

RISC Architecture:
The RISC architecture is a newer architecture that was developed in the 1980s. It is characterized by a smaller set of simple instructions that can only perform one operation at a time. This architecture is designed to reduce the complexity of the processor, making it faster and more efficient than the CISC architecture.

The smaller set of simple instructions also makes it easier to optimize the processor for specific applications, making it more cost-effective and reducing development time. In addition, the simpler instructions make it easier to design compilers that can translate high-level programming languages into machine language instructions.

Conclusion:
In summary, both the CISC and RISC architectures have been developed to reduce the semantic gap between high-level programming languages and low-level machine language instructions. However, the CISC architecture uses a larger set of complex instructions to reduce the number of instructions required to perform a task, while the RISC architecture uses a smaller set of simple instructions to reduce the complexity of the processor and make it more efficient.