The software provided with large computers supplies a hierarchy of languages; The assembler defines the language for describing the compiler and supervisor; the supervisor the language for job control; the compiler the language for application programs; the application program the language for its input. The user may not know, or know of, all these languages; but they are there. They stand between him and the computer, imposing their restrictions on what he can do and what it will cost.
And cost it does, for this vast hierarchy of languages requires a huge investment of man and machine time to produce, and an equally large effort to maintain. The cost of documenting these programs and of reading the documentation is enormous. And after all this effort the programs are still full of bugs, awkward to use and satisfying to no one.
We maintain that this multi-level nightmare is precisely that. We place the blame upon the lack of a suitable language. FORTH provides a suitable language, and by using it an order of magnitude improvement in the cost, effort and efficiency of providing a terminal interface.
We introduce a language with which a man at a keyboard can talk to a computer - man-machine communication. The reverse problem does not arise. The computer handles machine-man communication in rote fashion - typing specified replies.
We insert FORTH between man and machine and define 2 dictionaries: man-FORTH and FORTH-machine. The man-FORTH dictionary is a collection of documentation - of which this is a part - that teaches the man how to express his thoughts in FORTH.
The FORTH-machine dictionary is the subject of this paper, for it is the key to the dramatic success of FORTH.