The increasing complexity of computer systems often requires sharing of resources among many requestors or agents. The resource is often limited in its ability to service the agents, so some type of arbitration is necessary when two or more agents make simultaneous requests for the resource. Some resources such as for communications may require low latency while other resources such as for graphics may require high bandwidth.
Many types of arbitration have been used. A priority can be assigned to each agent, and when two or more agents make simultaneous requests, then the higher-priority agent is chosen to access the resource while the lower-priority agent is delayed. Such priority-based arbitration maximizes performance of higher-priority agents at the expense of lower-priority agents.
Another type of arbitration is fixed or round-robin arbitration. Each agent is assigned a time-slot or position in a loop, and is given highest priority during its time-slot or position in the loop. This type of arbitration is considered "fair" since all agents have equal access to the resource. Latency can be a problem since an agent may have to wait for its time-slot or turn in the loop. Various combinations with priority arbitration are possible to give some agents higher priority than others.
An area that is experiencing rapid technical advances is multimedia for computers, especially for personal computers (PCs). Multimedia includes graphics, video, and sound produced and manipulated by a computer. Different agents are used to process the different multimedia components.
Integration of PC telecommunications and data communication is also a rapidly-advancing field. PCs are often connected to telephone lines by modems or terminal adapters, and there is increased flow of multi-media data on Local Area Networks (LAN's). Such communications devices may need to respond to an incoming request quickly, with a low latency.