In this tutorial we are going to learn what micropocessor is and different technology used to design microprocessor i.e, CISC and RISC.
The progress to the VLSI technology led to the development of a microprocessor. The CPU also called microprocessor is the main IC chip on the computer’s motherboard, A microprocessor contains all the circuits needed to perform arithmetic logic and control functions. The core activities of a computer on a single chip are possible due to the development of microprocessor. Hence, it became possible to build a complete computer with a microprocessor a few additional storage and other supporting circuitry. A microprocessor has a limited number of instructions that it understands called its instruction set. Each instruction involves a series of logical operations (possibly thousands) that are performed to complete each task.
Most motherboards will accept more than one types of microprocessor as far as model manufacturer, and speed is concerned, but they generally accept only one socket type. This is a consideration that should be addressed and decided before we purchase either. The motherboard’s manual will tell us what different types of microprocessors it will accommodate. The major microprocessor manufacturers include Intel, Motorola, IBM, Advanced Micro Devices (AMD) and Cyrix.
The Central Processing Unit (microprocessor) is considered the ‘brain’ of the computer. It controls and directs all the activities of the computer, transmitting, receiving and processing data constantly, But like the ‘brain’ of any project or organization, it relies very heavily on its support group and advisors. There are a lot of factors involved related to the CPU and have an effect on the speed and performance of the machine. Some of these factors include:
- The clock speed of the system and microprocessor.
- The bus architecture of the microprocessor.
The following are the major microprocessor design technologies.
CISC technology (Complex Instruction Set Computing) combined the different instructions into one single CPU, and each instruction had the ability to perform several different tasks based on mini-programs or microcodes integrated into the processor. This technology would have its drawbacks. An increased number of instructions (200 to 300) meant a more complex processor, requiring millions of transistors. Instructions were of different lengths, using 8, 16, or 32 bits for storage. This resulted in a great deal of the processor’s time being spent calculating where each instruction began and ended.
It was discovered that some of the more complex instructions, and the mini-programs
(microcodes) integrated into CISC processors, were not entirely necessary. Using several of the less complex instructions together could complete the same tasks in less time. RISC technology (Reduced Instruction Set Computing) takes advantage of this. Using fewer instructions (128+) requires fewer transistors, which results in reduced manufacturing costs and is more stable, cooler operating CPU. Also, each instruction is of a fixed size (32 bits). This means that the processor doesn’t have to use up any of its valuable time figuring out where each instruction begins and ends. Intel’s microprocessors now use a hybrid of the both technologies.
The Math Coprocessor is a second processor in the computer that does nothing but number crunching for the system. Addition, subtraction, multiplication, and division of simple numbers are not the coprocessors jobs. It does all the calculations involving floating point (decimal) numbers, such as scientific calculations and algebraic functions. Having a second processor, or ‘coprocessor’, to take over the number crunching, it can free up a lot of the CPU’S precious time. This would allow the Central Processing Unit to focus all of its resources on the other functions it has to perform, thus increasing the overall speed and performance of the entire systems.
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