I/O facilities for SIMON, a VAX operating system simulator

Students of systems software need an environment in which to develop and test operating systems. Simulation, which gives the impression of access to normally privileged features, is a way to provide this environment; it is usually not economically feasible to dedicate a large multi-user computer for such purposes.

This thesis represents the third phase in the creation of SIMON, a VAX-11 operating system simulator. Facilities added during this phase permit students to test I/O services such as assigning channels and performing actual transfers using files that simulate printers and terminals. Simple screen and file I/O capabilities for debugging purposes have also been implemented.

The paper contains an overview of SIMON's previous two phases, an outline of VAX-11 I/O architecture and VMS I/O strategies, a presentation of the I/O facilities provided by SIMON, and two examples illustrating these facilities. Appendices contain reference guides for system space parameters, generic program form, extended operations, and other invariants of the testing environment.