Interface control process between using programs and shared hardware

Abstract

A control process which enables a non-supervisory 'using program' (e.g. application programs) to directly interface one or more shared asynchronous hardware facilities in a computer system. Any using program may request the operating system (OS) to set up a 'special environment' with an AHF during which the using program can directly issue requests to the AHF for its services. The OS sets up a session for the using program having the 'special environment', which specifies restrictions on storage accesses by the AHF for accesses made on behalf of the using program--to insure system data integrity. These restrictions are not changeable by the using program. The 'special environment' exists until the session is ended by the using program or by a terminating condition. The 'special environment' is tailored to be different among the different using program concurrently using the same AHF, so that the 'special environment' of one using program cannot interfere with the 'special environment' of another using program. During a session, work requests for any using program are communicated directly to the AHF from the using program, and completion of any work request is communicated directly by the AHF to the using program without any interruption of the using program or OS involvement.