The simplest way to examine the advantages and disadvantages of RISC architecture is by contrasting it with it’s predecessor: CISC (Complex Instruction Set. RISC and CISC Architectures – Difference, Advantages and . Disadvantages of CISC Architecture: Disadvantages of RISC Architecture. RISC and CISC are two architectures used for designing of Advantages of CISC Architecture Disadvantages of RISC Architecture.

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It closely resembles a command in a higher level language. The figure shown above is the architecture of RISC processor, which uses separate instruction and data disadvantzges and their access paths also different.

RISC and CISC Architectures – Difference, Advantages and Disadvantages

This architecture necessitates on-chip hardware to be continuously reprogrammed. The overall performance of or machine is reduced due to the different amount of clock time required by different instructions.

The operand is a memory register where instruction applied. He has 8 years of experience in Customer Support, Operations and Administration. It consists of complex instructions that take multiple cycles to execute. A machine cycle is defined as the time taken to disadvaantages two operands from registers, perform ALU operation and store the result in a register.

CISC – Advantages and disadvantages table in A Level and IB Computing

There is one instruction per machine cycle in RISC processor. This entry was posted in Uncategorized. To solve these problems, the number of instructions per disadvntages can be reduced by embedding the number of operations in a single instruction, thereby making the instructions more complex. Thus, they share the same path for both instructions and data. The main aim of designing CISC based processors is to build the processor with more complex instruction set.


The microinstructions are executed one by one and in turn necessary control signals for the execution of an instruction are produced in steps.

Due to this one cycle instruction, execution of instructions carried at a faster rate compared with microinstructions on CISC processor.

The per-chip cost is reduced by this architecture that uses smaller chips consisting of more components on a single silicon wafer. Disadvantages of CISC architecture. The complexity of hardware and on-chip software included in CISC design to perform many functions. In RISC architecture, the instruction set of the computer is simplified to reduce the execution time.

This architecture uses unified cache memory for holding both data and instructions. This architecture uses less chip space due to reduced instruction set. These cycles fetch, decode and execute of one or more instructions are overlapped in this pipeline technique. These have many instruction formats and many addressing modes.

What is RISC and CISC Architecture with Advantages and Disadvantages

However, the execution unit can only operate on data that has been loaded into one of the six registers A, B, C, D, E, or F. By this evolution the semantic gap grows. Leave a Reply Cancel reply Enter your comment here So the compiler development was time consuming and tricky. Microprogramming is easy to implement and much less expensive than hard wiring a control unit.


In order to make easy development of the compiler, CISC was developed. It has higher number of addressing modes, typically 12 to To find out more, including how to control cookies, see here: CISC has the ability to execute addressing modes or multi-step operations within one instruction set. The above figure shows the architecture of CISC with microprogrammed control and cache memory. The important aspect of computer architecture or any other microprocessor device is the design of the instruction set for the processor.

Includes multi-clock complex instructions. The execution unit is responsible for carrying out all computations.

Instructions are not pipelined or less pipelined. Instruction formats have variable length.

The processor is controlled by a hardwired control without control memory. It is performed by overlapping the execution of several instructions in a pipeline fashion. In CISC processor, most instructions are stored in memory and they are executed by microprogram.

This site uses cookies. You can Contact Us. Group of instructions given to execute the program and they direct the advantabes by manipulating the data. Because there are more lines of code, more RAM is needed to store the assembly level instructions.