1. BY SEMIRINDI MAKALA Plan to Throw One Away

2. Pilot Plants and Scaling up What is a pilot plant ? A pilot plant is an intermediate step that is necessary to give experience in scaling up quantities. For example, a laboratory process for desalting water will be tested in a pilot plan of 10,000 gallon/day capacity before being used for a 2,000,000 gallon/day water system.

3. Pilot Plan and Scaling up cont Programming system builders have also been exposed to this lesson. In most projects, the first system built is barely usable. When a new computer system is used, one has to first build a system to throw it away. We’re not likely to get it right the first time, there are always BUGS !

4. The throw-one- away concept is itself just an acceptance of the fact that as we learn, we change the design and this can also be applied to software engineering.

5. Plan the System for Change The ways we can design a system for such change are: Careful organizations into modules for more flexibility Extensive instruction sequence in a machine that can be pre-written and referred to as often as needed ( extensive sub routining)

6. Plan the System for Change con’t The ways we can design a system for such change are: Quantization of change involving the following: Numbered version of each product Each version has its own schedule Freeze date after which changes go into the next version

7. Two Steps Forward and One Step Back A program doesn’t stop changing after it’s delivered for costumer use. Program maintenance are the changes after delivery. Cost of maintenance typically cost 40 percent or more of the cost of developing it Old bugs found and solved in previous releases tend to reappear in a new release.

8. One Step Forward One Step Back All repairs tend to destroy the structure to increase disorder of the system More is spent on fixing earlier flaws introduced by earlier fixes. Machines change, configurations & user requirements change which makes the system not usable forever A brand new, from the ground up redesign is necessary.

9. Conclusion There is always going to be change needed to be made after building a computer program. Changes make us learn more about taking a better approach at building programs with fewer bugs or inconveniences