Access method

An access method is a function of a mainframe operating system that enables access to data on disk, tape or other external devices. Access methods were present in several mainframe operating systems since the late 1950s, under a variety of names; the name access method was introduced in 1963 in the IBM OS/360 operating system.[1] Access methods provide an application programming interface (API) for programmers to transfer data to or from device, and could be compared to device drivers in non-mainframe operating systems, but typically provide a greater level of functionality.