A base address is used by computer programs to identify an originating location or starting point. It might be the first set of instructions in a series of programming commands. Sometimes a base address is used to indicate locations of specific hardware components, such as a printer or external storage disk.
Computers use different address schemes in order to process and complete certain functions. Devices may be assigned addresses that use a base address as a reference. For example, an external drive may be assigned an address of two since it is in the second place where the program can locate data. The address would not just include the number two, but also the base address, which may be as simple as a series of zeros. Computer memory uses address schemes to identify locations of peripheral devices, internal random access memory, and reserved hard drive space.
The idea of a base address can be thought of as a sequence. It is a signal or code to the computer and its programs to operate in a certain fashion. For example, a word processing program might first attempt to communicate with a printer before sending a document to its queue. The base address or reference for these set of instructions would be assigned to some sort of command that prompts a communication test.
After the word processing application has established that the printer is on and able to receive communication, it would proceed to the next step. The application would recognize that sending the document to the print queue is the next step since the base address plus two is assigned to that particular command function. Following the completion of the second step, the program would reference the same base or reference address in the third command.
Relative addresses are all of the address assignments that use the reference address. The absolute address is equivalent to the reference or starting point. Eight-bit and 16-bit processors already have a fixed address sequence and do not usually require the manual input of a reference address. 32-bit processing systems, however, will.
Regardless of where the reference address is located in a computer's memory scheme, it will almost always begin with an assignment of zero or one. Sometimes letters are used to assign a base address, but they are usually done in a repetitive or synchronistic manner. Many 32-bit programs prompt for the manual assignment and creation of a reference address or starting point.