![]() One hertz is one cycle per second - but the computer runs at gigahertz speeds - this is one billion cycles per second. To coordinate all of these different actions, an electronic clock makes everything run at the same time and in sync. ![]() The CPU is very complex and there are often several things happening at once. The computer system will continue to run through the FDE cycle all the time that the power is turned on. You need to know about the following CPU components:Īnd you also need to know these specific Von Neumann architecture components: You should memorise the phrase "The purpose of the CPU is to fetch, decode and execute instructions" as this question will appear frequently on exam papers. Once they have been decoded, they will be executed. Instructions are firstly fetched from memory, and then decoded in the control unit. You will need to know how the Von Neumann architecture works in a CPU, and the names of the main components that it uses. The program is stored in memory (often loaded from a hard drive), and the instructions are fetched, decoded and executed, and a single control unit controls the flow of program instructions and data around the system. His designs include the concept of having a program that is stored and is executed when the computer runs. Most modern personal computers are single processor systems while multiprocessors are used in niche systems only.John Von Neumann was a mathematician and physicist who studied how to design a computer and came us with a system that is used almost universally in modern computer systems.At most the throughput of the system decreases a little. In multiprocessor systems, even if one processor fails than the rest of the processors can pick up the slack. Single processor systems are less reliable than multiprocessor systems because if the processor fails for some reason then system cannot work.However, if the throughput of n single processor systems is T then the throughput of n processor multiprocessor system will be less than T. Throughput of a multiprocessor system is more than a single processor system.This is because all the processors in the multiprocessor system need to be synchronized and this can be quite complicated. It is easier to design a single processor system as compared to a multiprocessor system.If n processor multiprocessor system is available, it is cheaper than n different single processor systems because the memory, peripherals etc. Single processor systems can be more expensive than multiprocessor systems.This can be done in symmetric or asymmetric multiprocessing. On the other hand, multiprocessor systems have many processors that can perform different tasks. Single processor systems use different controllers for completing special tasks such as DMA (Direct Memory Access) Controller.Single processor system contains only one processor while multiprocessor systems may contain two or more processors.There are many differences between single processor and multiprocessor systems.Some of these are illustrated as follows − Differences Between Single Processor and Multiprocessor Systems However, the system contains a single processor and only one process can be executed at a time. Most general purpose computers contain the single processor systems as they are commonly in use.Ī single processor system can be further described using the diagram below −Īs in the above diagram, there are multiple applications that need to be executed. So only one process can be executed at a time and then the process is selected from the ready queue. A single processor system contains only one processor.
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