SATELLITE GRAPHICS SYSTEM FOR ERROR-PRONE USERS

A system is described which is used at Florida International University in support of an undergraduate course in interactive computer graphics. The equipment configuration consists of an IMLAC PDS-4 with 8K of memory connected to a UNIVAC 1106 via a 1200 baud asynchronous communications line. In addition, a simple unbuffered and unintelligent alphanumeric CRI terminal (a Beehive model II) is connected to another I/O port on the IMLAC PDS-4 via a 1200 baud interface. The GCS system is used on the host 1106 for the students. Because of the numerous errors committed by the beginning students, the problem exists of numerous unexpected program errors, dumps and of the need for debugging information to be presented to the students, all without effecting the graphical display. The graphical data sent from the UNIVAC 1106 is encoded in such a way that the software in the IMLAC PDS-4 can separate out any non-graphical data sent, no matter where it appears in the output stream. The non-graphical output is then displayed on the auxiliary terminal. This allows the students to include debugging output and also to receive and analyze error messages, dumps and the like while maintining the integrity of any graphical output also produced by their programs. This system has proved especially useful for error-prone beginning students, at minimal costs and with no modifications to the EXEC-8 operating system. © 1979.