Abstract: A distributed data processing system is provided in which two computers, each running under a different operating system, are coupled so that jobs initiated by a first one of the computers can be executed on a second computer by using the resources of the second computer. This enables the user of the first computer to use the second computer under the environment of the first computer. The first computer acts as the interface between the user and the data processing system. Service programs running on the system can handle or provide for input/output operations during the execution of jobs on the second computer so that the jobs seem to the user of the first computer to be executed on the first computer. The system has means for creating a dummy file in the file system of one operating system which is used as a place holder for a corresponding file in a storage device attached to the other operating system, and accessed by programs controlled by that other operating system.