A Low Cost Satellite for Fast Interactive Graphics in a Time-Sharing Environment

This paper describes a system that improves the performance of a time-shared host computer for users of TEKTRONIX series 4010/4014/4015 graphics terminals. The system consists of a mini or microcomputer situated at the terminal, a program that runs in the satellite computer, and a library of FORTRAN callable subroutines that provide a convenient interface between an application program in the host computer and the program in the satellite computer. The system ensures that the satellite has advance information about the expected dialogue, so that the satellite is able to react instantly to input from the user, even if the response of the host computer is slow. The satellite gathers several trivial inputs together and sends them to the host in a burst. This allows the program in the host to process more information each time it is rolled into memory, hence the efficiency of its operation is improved. The satellite also performs such operations as zooming, repainting and identification of entites on the screen.