1. FOREWORD FORTH is an integrated programming approach and computer language. FORTH was invented by Mr. Charles Moore specifically to increase programmer productivity in the development of computer related applications without sacrificing machine efficiency. FORTH is a layered environment containing the elements of a computer language as well as those of an operating system and a machine monitor. This extensible, layered environment provides for highly interactive program development and testing. In the interests of transportability of application software written in FORTH, standardization efforts began in the mid-1970s by the European FORTH User's Group (EFUG). This effort resulted in the FORTH-77 Standard. As the language continued to evolve, an interim FORTH-78 Standard was published by the FORTH Standards Team. Following FORTH Standards Team meetings in 1979 the FORTH- 79 Standard was published in 1980. The FORTH Standards Team is comprised of individuals who have a great variety of experience and technical expertise with FORTH. The FORTH Standards Team consists of both users and implementers. Comments, proposals, and correspondence should be mailed to: FORTH Standards Team, P.O. Box 4545, Mountain View, CA 94040 USA. FORTH's extensibility allows the language to be expanded and adapted to special needs and different hardware systems. A programmer or vendor may choose to strictly adhere with the standard, but the choice to deviate is acknowledged as beneficial and sometimes necessary. If the standard does not explicitly specify a requirement or restriction, a system or application may utilize any choice without sacrificing compliance to the standard provided that the system or application remains transportable and obeys the other requirements of the standard.