Address space

In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity.

Overview

For software programs to save and retrieve data, each unit of data must have an address where it can be individually located. The number of address spaces available will depend on the underlying address structure and these will usually be limited.

Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous (within a particular address space). For a person's physical address, the address space would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of an address space may be the same– but if any element in the address is different than addresses in said space will reference different entities. An example could be that there are multiple buildings at the same address of "32 Main Street" but in different towns, demonstrating that different towns have different, although similarly arranged, street address spaces.

Enhanced 9-1-1

Enhanced 911, E-911 or E911 is a system used in North America that links emergency callers with the appropriate public resources. Three-digit emergency telephone numbers originated in the United Kingdom in 1937 and have spread to continents and countries around the globe. Other easy dial codes, including the 112 number adopted by the European Union in 1991, have been deployed to provide free-of-charge emergency calls.

In North America, where 9-1-1 was chosen as the easy access code, the system tries to automatically associate a location with the origin of the call. This location may be a physical address or other geographic reference information such as X/Y map coordinates. The caller's telephone number is used in numerous manners to track a location that can be used to dispatch police, fire, emergency medical and other response resources. Automatic location of the emergency makes it faster to locate the required resources during fires, break-ins, kidnappings, and other events where communicating one's location is difficult or impossible.