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Compare RISC and CISC architecture.
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written 8.2 years ago by |
- | RISC | CISC |
---|---|---|
1 | RISC stands for Reduced Instruction Set Computer | CISC stands for Complex Instruction Set Computer |
2 | RISC processors have simple instructions taking about one clock cycle. The average Clock cycles Per Instruction(CPI) of a RISC processor is 1.5 | CISC processors have complex instructions that take up multiple clock cycles for execution. The average Clock cycles Per Instruction of a CISC processor is between 2 and 15 |
3 | There are hardly any instructions that refer memory. | Most of the instructions refer memory |
4 | RISC processors have a fixed instruction format | CISC processors have variable instruction format. |
5 | The instruction set is reduced i.e. it has only few instructions in the instruction set. Many of these instructions are very primitive. | The instruction set has a variety of different instructions that can be used for complex operations. |
6 | RISC has fewer addressing modes and most of the instructions in the instruction set have register to register addressing mode. | CISC has many different addressing modes and can thus be used to represent higher level programming language statements more efficiently. |
7 | Complex addressing modes are synthesized using software. | CISC already supports complex addressing modes |
8 | Multiple register sets are present | Only has a single register set |
9 | RISC processors are highly pipelined | They are normally not pipelined or less pipelined |
10 | The complexity of RISC lies in the compiler that executes the program. | The complexity lies in the micro program |
11 | The most common RISC microprocessors are Alpha, ARC, ARM, AVR, MIPS, PA-RISC, PIC, Power Architecture, and SPARC. | Examples of CISC processors are the System/360, VAX, PDP-11, Motorola 68000 family, AMD and Intel x86 CPUs. |