DDL(ID:5294/ddl004)

Drawing Descriptive Language 

for Drawing Descriptive Language

North American Aicraft drafting language, forerunner of Autodraft
Related languages
APT => DDL   Influence
DDL => AUTODRAFT   Evolution of
References:
  • Smith, O. D. and Harris, H. R. "Autodraft: A language and processor for design and drafting" view details Abstract: Autodraft is a system designed for the use of designers and drafts-men in accomplishing graphics with the aid of a computer. The system was developed jointly by North American Aviation, Inc., and International Business Machines using the facilities of the Los Angeles Division of NAA, namely the IBM 7094 computer and the S-C 40Z0 printer/plotter as output.
    Extract: Introduction
    With the limitations imposed by the hardware available, the only reasonable means of input was some type of programming language with which the draftsman could instruct the computer as to how he wanted a drawing made. This mode of input had the advantage that it could work easily in the batch-process environment of the 7094, but could later be changed to a remote typewriter mode, and perhaps even a console-light pen type of operation. Consequently, a language was developed called the "Drawing Descriptive Language" (DDL), denoting that the language described how to make a drawing, not how a three-dimensional object was constructed.
    The specification of a processor similar to that used in APT was dictated partly by the decision to use a programming language input to the system, and partly by the requirement to be able to easily adapt the system to varieties of plotting equipment. Therefore, as in APT, an input translator was developed to translate the language, and a geometric processor to perform the essential calculations, both of which are independent of the specific plotting device to be used. The last portion of the program is a postprocessor which performs all the calculations dependent upon the plotting device.
    Perhaps the most important system characteristic defined was that of file capability. This includes the capability to store pre-coded configurations such as standard-parts to be called as required, basic information about the product being designed which must be available to all the designers and draftsmen on aparticular project, and all the coded drawings themselves for purposes of making revisions, design changes, and usage of the information for other purposes such as tooling and numerical control. As previously indicated, file capability appears to be the most important system characteristic since economic analysis makes it evident that the ability to store and retrieve design information is the crux of that the ability to store and retrieve design information is the crux of economic justification of any computer-aided design or drafting system.
          in [ACM/IEEE] Proceedings of the SHARE Design Automation Project Annual ACM IEEE Design Automation Conference 1965 view details