Enclosed was a schedule for further development, with the comment, "The major portion of the items are enhancements, and there is no really urgent modification that we cannot live without."
No Fenwick Software personnel were present when the system was installed, and none has been to Boyne Island since. The maintenance programmer — a new graduate who trained with Fenwick Software for a year before shifting to Queensland — devoted most of his time in the first months after installation linking special data capture terminals into the system.
A "Humanised" System
In the manual system, the person in control of the casting area is the "metal coordinator". Starting from a long-term production schedule prepared by marketing, he decides what products are going to be made on which bits of equipment. He then allocates appropriate grades of metal coming from the smelter to the various furnaces and calculates the additives required to bring each furnace of metal to the correct chemical composition for the alloy being made.
We discovered that the experienced metal co-ordinators exhibited great skill in performing this task. Not only did they carry a surprising amount of quantitative information in their heads, such as the tolerance limits for the various elements in all the common alloys, and which additives to use, but their decisions were also influenced by factors like who was the leading hand on the furnace and who had been working on the previous shift.
We determined that our system would assist an inexperienced co-ordinator to do a competent job, but at the same time allow the more experienced people to exercise their skills. Thus, the whole system works by suggesting a solution which the user can accept, modify or discard completely. All the tedious calculations are done by the system, reducing the chance of careless mistakes. But the user retains the capacity to adjust the automatically generated figures at every stage. 'Only exception data is keyed, keeping data entry effort to a minimum.
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Methodology
Anyone who is convinced that there is one methodology which will provide a magic solution to all system development problems will be disappointed by our experience. IMPAC was developed without the benefit of any of the much-publicised project control methodologies. We did, however, make extensive use of structured programming, structured design and structured analysis, have been used by Fenwick Software since the company began in 1976. With some slight adaptation to our needs, we have found these techniques extremely effective. The data flow diagrams are an excellent tool for communicating and exchanging ideas with the users and structured design and structured programming ensure that the finished product is robust, reliable and easy to modify or enhance. More details of the structured techniques and the way they were managed are included later in this paper.
Critical Factors in IMPAC's Success
For future reference, we were very interested in identifying the things which contributed to the success of the project. The factors identified, and their relative importance, are as follows:
A. Vital
User involvement
Depth of analysis
Reliable, dedicated hardware
Prototyping
B. Significant
Structured systems development
Productivity tools
Project control
C. Helpful
Realistic budget
Ongoing documentation
Teamwork
User Involvement
The most significant factor contributing to the success of IMPAC was the degree of user involvement. BSL assigned Murray Doyle, the project estimator of the smelter project, as its user
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