MIcroprocessors process the data using instructions. It retrieves the data and instructions From the RAM. Micrprocessor can be classified into two types CISC and RISC based on the number of instructions built into it.
Complex Instruction Set Computing (CISC) - The microprocessor using cisc archotectur have many instructions build into it.This saves the processing time for performing tasks. The time is saved Because the required instructions are available in the microprocessor itself and it does not have to receive the instructions from the program stored in the external memory , such as the RAM.
The CISC architectur helps the microprocessor to speed up the execution of programs requiring instructions. However , the instructionsbuilt into the microprocessor affects the performance of the microprocessor . This is because more time taken to process the instructionsand also the space availableon the microprocessor for processing reduces.To overcome this problem more transistors need to be built into the microprocessor to maintain the speed of microprocessor.
Reduced Instruction Set Computing (RISC)- The cisc MIcroprocessor have the instructions built in the microprocessor. These instructions take up space in the microprocessor and leaves less space for program processing. Some microprocessors perform specific tasks, such as those used for performing scientific calculations. The extra instructions built into the microprocessor take up valuable space in the microprocessor. The processing time taken to execute the extra instructions is also wasted.
To overcome these problems , a new architectur called RISC came into picture.The microprocessors using RISC architecture have limited instructions built in it. These requires few transistors to be built into the microprocessor to make up for the time delay in processing the instructions. The reduction in instructions also saves the space in the microprocessor. The RISC microprocessor is cheaper to nuild than the CISC microprocessor.