HYBRID—a user-developed hybrid interpretive language

Abstract

An interpretive hybrid programming language, HYBRID, has been developed by The Foxboro Company, for use in a small hybrid computer system. The TELETYPE* oriented language comprises a command structure resembling FOCAL and offers hybrid instructions similar to HOI. It provides features seldom found in software for small (mini) computers with limited core, such as computed (variable) part and step numbers in go-to instructions, foreground- background operational modes, monitor functions, and a full assortment of hybrid and interrupt handling capabilities. The HYBRID program occupies approximately 4K of core in a PDP-7t 18-bit computer and includes routines for drum (disc) and paper tape input- output of source and data files. It permits the use of assembly (machine) language routines to be called by source program commands. The variable list (Symbol Table) is referenced in a binary search mode, which results in fast execution speed as well as efficient running of the source program. The language contains a number of error-checking and source-program protection provisions to make it as user-friendly and fault-tolerant as possible .