RISC and CISC Processors
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CISC processors have a large number of complex instructions that can perform operations directly from memory to memory. In contrast, RISC processors have a small set of simple instructions that operate only within registers, with load and store as separate instructions. The first RISC projects in the late 1970s-early 1980s from IBM, Stanford, and UC-Berkeley aimed for single-cycle execution with a fixed-length instruction format. RISC emphasizes hardware simplicity while CISC focuses on smaller code size and higher cycles per second.
RISC and CISC Processors
- 1. CISC & RISC
- 3. What is CISC? A computer with a large number of instructions is classified as a Complex Instruction set Computer, abbreviated CISC What is RISC? RISC, or Reduced Instruction Set Computer. is a type of microprocessor architecture that utilizes a small, highly-optimized set of instructions, rather than a more specialized set of instructions often found in other types of architectures.
- 4. History The first RISC projects came from IBM, Stanford, and UC-Berkeley in the late 70s and early 80s. The IBM 801, Stanford MIPS, and Berkeley RISC 1 and 2 were all designed with a similar philosophy NEXT Invent CISC. For more Complex instructions.
- 5. Characteristics of RISC Processor Register to Register "LOAD" & "STORE" are independent instructions. Relatively few addressing modes. All operations done within the registers of the CPU Fixed-Length, Easily decoded instruction format Single-Cycle instruction execution
- 6. Characteristics of CISC Processor Emphasis on Hardware. Includes multi-clock complex instructions. Memory-to-memory “LOAD” and “STORE” incorporated in instructions. Small code size, high cycles per second
- 7. RISC & CISC Approaches The CISC Approach The RISC Approach
- 8. Overlapped Register Windows Global Register Local Register Overlapped Register