CADES
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CADES

CADES (Computer Aided Design and Evaluation System) was a software engineering system produced to support the design and development of the VME/B Operating System for the ICL New Range - subsequently 2900 - computers.

From its earliest days, VME/B was developed with the aid of CADES, which was built for the purpose using an underlying IDMS database (latterly upgraded to IDMS(X)). CADES was not merely a version control system for code modules: it was intended to manage all aspects of the software lifecycle from requirements capture through to field maintenance.

It was the design of CADES that paved the way for the Alvey Project in IPSE (Integrated Project Support Environments) and Process Control Engines. Because CADES was used for more than 20 years throughout the development of a large software engineering project, the data collected has been used as input to a number of studies of software evolution.

CADES was conceived in 1970 by David Pearson and Brian Warboys when working for ICL's New Range Operating System Technology Centre, OSTECH, in Kidsgrove. Pearson, a theoretical physicist by training, had become a computer simulation specialist and joined ICL in 1968 after working in finite-element modelling at Cambridge and simulation research at Imperial College. Warboys had been chief architect for the ICL System 4 multi-access operating system, Multijob.

ICL's commitment to large scale software development for the 2900 Series of computers provided the basis for the Pearson and Warboys early work on a new software development environment which would address the issues of designer/programmer productivity, design integrity, evaluation and testing, version control and systems regression.

In designing the initial architecture of the CADES environment, Pearson in particular looked to parallels with the leading hardware computer-aided design systems of the time, even attempting the use of graphics in the design process. The CADES design approach, called Structural Modelling, was rigidly data-driven and hierarchical, and expressed in a formal design language, SDL. Design specifications written in SDL were processed by the Design Analyser, before being input to the CADES Product Database, a design and implementation database supporting its own query language and forming the kernel of the Product Information System.

The intention was that these designs could be evaluated/simulated using the Animator, and S3 implementation code automatically generated from them using the Environment Processor. Build generation and version control was also based on the Product Database, resulting in a highly disciplined approach to new system builds. System Regression was therefore controlled from a very early stage in the software life-cycle.

In order to control the development of VME/B, each development was sub-divided for easier management. The structure was hierarchic, with each significant components of VME (kernel, file store, etc.)divided into sub-systems. Development activity on each sub-system created a sequence of versions.

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