A uniprocessor system has a single computer processor, while multiprocessor systems have two or more. The term "multicore" is also used to describe multiprocessor systems. Multiprocessor systems can lead to better performance, although they must be managed carefully to exploit their power fully.
Physical limitations often limit how fast a particular processor design can operate. For instance, Intel initially wanted to produce chips based on their Pentium 4 design to operate at 10 GHz, but problems with heat dissipation limited these chips to just 3.8 GHz. Multiprocessor systems allow processors to use more space, which provides better heat dissipation.
However, computers are rarely able to fully exploit all the power provided by multicore systems. Calculations that cannot be broken into two separate parts can only run on one processor. In some cases, one processor might have to wait for information to be calculated on another processor before proceeding. Amdahl's Law, first presented in 1967, demonstrates that expected real-world results lead to diminishing returns when more processors are added to a system.
Despite these limitations, multiprocessor systems are common on sophisticated devices. Smartphones can reserve one processor for handling phone calls while using other processors for user applications and interaction, which ensures that the resources needed for handling phone calls are available regardless of what the user is doing.