UNIX to DEC-10: a simple teleprocessing link

This work is part of a thesis project for the Master of Science degree in Computer Science. The objective of the project is to create a software link between a PDP-11/34 minicomputer running under the UNIX operating system and a DEC-10, both at the University of Tennessee at Knoxville.This link provides the PDP-11 users the capability of batch job submission to the DEC-10. The hardware involved is minimal -either machine views the other as a simple terminal. The actual software that handles the communication is a simple process, not part of the operating system, per se.A special device driver routine (added to the operating system) is necessary to handle the I/O under UNIX. The existing device driver routine has a limited buffer size of 256 characters. The communication software which reads this buffer competes for machine resources with the same priority as other user processes. Therefore, a buffer overrun and consequent information loss can occur unless the output of the DEC-10 is automatically inhibited by the device driver until buffer space is available.At any time, a user of the PDP-11 can submit a file of commands to be interpreted line by line by either the DEC system or the UNIX system. This submission merely results in the request being queued as a batch process to be later initiated by an operator. When initiated by the operator, the queue of requests is serviced individually by first logging into the requesting user's DEC account (this information is system maintained). Any output produced by the DEC system is stored in a file with the entry in the user's directory. The entire implementation is in the C language.