Browse Prior Art Database

Graphic Programming Language

IP.com Disclosure Number: IPCOM000045993D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 4 page(s) / 18K

Publishing Venue

IBM

Related People

Lippmann, HE: AUTHOR

Abstract

The requirements and structure of a Graphic Programming Language (GPL) which replaces "keywords" with standard flowline structures or flowchart diagrams are described.

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This is the abbreviated version, containing approximately 40% of the total text.

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Graphic Programming Language

The requirements and structure of a Graphic Programming Language (GPL) which replaces "keywords" with standard flowline structures or flowchart diagrams are described.

basic concept

Virtually all programming languages are predicated on a lineby-- line form of input to the computer. At first, these languages had to be embodied in punched cards. Later, lines could be entered on a terminal and stored in data sets. Still, expression by a series of character strings persisted. Among these languages are Assembler, FORTRAN, PL/I, COBOL, PASCAL and APL.

However, many of the structures of programming are, precedent aside, more naturally expressed graphically, as the early developmentof flowcharts testifies. But flowcharts never became the basic source for compilers as did the series-of- text-strings because the technology for their maintenance did not exist in earlier times.

With the lowering of the cost of graphic terminals, it now becomes more feasible to use such terminals as programmer work-stations. Therefore, it has become practical to develop a programming language which replaces keywords, such as IF, THEN, ELSE, DO, END, TO, BY, WHILE, UNTIL, ITERATE, LEAVE and CALL, with flowline structures which show the flow of control more graphically.

implementation requirements

STRUCTURES

The flowchart-like structures developed for this language are required to have certain characteristics in order to implement the concept. All structures must have a single entry point at the top. Most have a single exit at the bottom aligned with that at the top. The exceptions are GOTO, LEAVE, and ITERATE. Thus, a sequence of these structures becomes connected except where these exceptions occur.

NESTING

The structures that allow others to be nested within them, such as IF-THEN- ELSE and DO, must have a gap at the appropriate latitudes, with an exit at the top of the gap and an entrance at the bottom of the gap at the same longitude. This allows any structure to nest in a gap by offsetting the nested structure so that the exit from the mother to the daughter structure is aligned with the entrace to the daughter structure.

CHARACTER-STRING INPUT

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Still expressed in character strings are assignment statements, I/O statements, propositions (i.e., IF, WHILE, and UNTIL clauses), CALL argument lists, and declarations.

Assignment statements and I/O statements do carry flow through themselves, always directly through from entrance to exit.

A proposition is not in the line of flow, but lies beside a point of divergence, according to the format of each structure having a divergence.

CALL argument lists are treated in a manner similar to that of a proposition.

STORAGE OF SOURCE

A format is needed for the storage of a GPL program. The medium should be a series of 72-byte records for compatibility with library systems that store source for other languages. And the values placed in those bytes are restricted to the EBCDIC charact...