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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Intel ccisc It was launched in the year and it is a CISC processor, which has instructions varying lengths from 1 to 11 and it will have instructions. Because there are more lines of code, more RAM is needed to store the assembly level instructions.

The major characteristics of CISC architecture are.

What is RISC and CISC Architecture ? Edgefxkits

It supports complex addressing modes. CISC incorporates an instruction with variable length format. This architecture uses less chip space due advantges reduced instruction set. They provide a high level of abstraction, conciseness and power.

Hard-wired control amd than micro programmed. Hardware architecture may be implemented to be either hardware specific or software specific, but according to the application both are used in the required quantity.

The above figure shows the architecture of CISC with microprogrammed control and cache memory. This architecture uses unified cache memory for holding both data and instructions. The main memory is divided into locations numbered from row 1: You are commenting using your WordPress.


Ad feeding the instructions, they require very fast memory systems. RISC processors take simple instructions and are executed within a clock cycle. Thus, the entire task of multiplying two numbers can be completed with one instruction: You are commenting using your Twitter account. Leave a Reply Cancel reply Enter your comment here Because, sisadvantages large programs need more storage, thus increasing the memory cost and large memory becomes more expensive.

In CISC processor, most instructions are stored in memory and they are executed by microprogram. The riec is controlled using microcoded control memory modern CISC processor also uses hardwired control. CISC design is a 32 bit processor and four bit floating point registers. The data is loaded into one of four registers A, B, C, or D. This architecture makes the efficient use of main memory since the complexity or more capability of instruction allows to use less number of instructions to achieve a given task.

Instructions are not pipelined or less pipelined. Idsadvantages, CISC has the variable length encoding of instructions and the number of clock cycles required to execute the instructions may be varied. Many RISC processors use the registers for passing arguments and holding the local variables. In order to make easy development of the compiler, CISC was developed. CISC designs involve very complex architectures, including a large number of instructions and addressing modes, whereas RISC designs involve simplified instruction set and adapt it to the real requirements of user programs.


The instruction set architecture is the part of the processor which is necessary for creating machine level programs to perform any mathematical or logical operations. Disadvantages of CISC architecture. In this complex addressing modes are abd in software. A machine cycle is defined as the time taken to fetch two operands from registers, perform ALU operation and store the result in a register.

When executed, this instruction loads the two values into separate registers, multiplies the operands in the execution unit, and then stores the product in the anv register. You Might Also Like. Instruction Count of the CPU.

Complexity lies the compiler. To find out more, including how to control cookies, see here: 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.

You can Contact Us. The overall performance of the machine is reduced due to the different amount of clock time required by different instructions.

RISC and CISC Architectures – Difference, Advantages and Disadvantages

It uses small and highly optimized set of instructions which are generally register to register operations. This entry was posted in Uncategorized.

Only load and store instructions have memory access.