What are the differences between RISC and CISC architecture?

difference between RISC and CISC architecture

Differentiate between CISC and RISC?

In this article you will learn about major differences between RISC and CISC architecture. First lets see what is the RISC and CISC architecture.


RISC is the abbreviation of Reduced Instruction Set Computer; it is speedy and compact as its name indicates. It follows the pipelining procedure and normally it can execute one instruction in one machine cycle.

Its diagram is given as:

RISC architecture
RISC architecture

RISC is mainly used for general instructions. It doesn’t perform complex operations.


CISC architecture or CISC is abbreviated as Complex Instruction Set Computer. It is not as fast as compared to RISC and not as efficient either but that’s not the reason of its innovation. It was invented so that complex or instructions that are not followed by RISC of user can be implemented.

It also follows the pipeline procedure, but it is slow.

CISC Architecture
CISC Architecture
Many instructions are present in the architecture Very few instructions are present. The number of instructions is generally less than 100
Some instructions with long execution. times. These include. instructions that copy an entire block from one part of memory to another and others that copy multiple registers to and from memory. No instruction with a long execution time due to a very simple instruction set. Some early RISC machines did not have an integer multiple instruction requiring compilers to implement multiplication as a Sequence of additions.
Variable-length encodings of the instructions are used

Example: IA327 instruction size can range from 1to 15 bytes.

Fixed length encodings of instructions are used.

Example: IA32, generally all instructions are encoded as 4 bytes.

Multiple formats are supported for

Specifying operands.

Simple addressing. formats are supported
CISC Supports aways. RISC does not support an away
Arithmetic and logical operations can be applied to both memory and register operands Arithmetic and logical operations only use register operands.
Implementation programs are hidden from machine-level programs. Implementation programs are exposed to machine. level programs.
Condition codes au used No condition Codes are used.
The stack is being used for procedure arguments and return addresses. Registers are being used for procedure arguments and return addresses.
difference between RISC and CISC
difference between RISC and CISC

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