1. The Systems Life Cycle: Implementation
Introducing the system to the place it will be used

2. Implementation
Once the system is ready there are 4 main ways of implementing it.
Parallel running
Direct changeover
Phased implementation
Pilot running

3. Direct changeover Switch off the old system and switch on the new.
Simplest scenario
Old systems switched off, new system takes over completely
Non critical systems only
the new system replaces the old system in one go
saves money in wages/very fast method of implementation
BUT
if anything goes wrong you don’t have the old system to fall back on
Cannot go back to old system if any problems

4. Parallel running
Both old and new systems run side by side till new system is working properly
Necessary in critical situations
If the new system breaks down you still have the old system as a backup
BUT
It can be a slow process/all tasks have to be performed twice
Expensive in terms of resources (may need two sets of staff)

5. Phased implementation
New system is brought in one section at a time
Can ensure each part of new system works properly before changing the next part
Eg new library system
BUT
Takes longer than direct changeover
If new system unsuccessful, may lose some data

6. Pilot running Eg in large banks or corporations
One branch changes to new system, identifies any problems
Other branches function as normal
Problems can be identified & solved before new system is rolled out to all branches
BUT
If new system unsuccessful, may lose some data

7. Summary Direct changeover
The old system is scrapped and immediately replaced by the new system. With this option there is a danger that there may still be problems with the new system. Even though it is the most risky type of changeover, many companies use this method.
Phased changeover
The change over is split into phases or stages. Each stage is introduced one at a time and the old system is kept running to do the remainder of the tasks that have not yet been changed.

8. Summary (continued) Parallel running
Running both the old and new system until you are certain the new system is working correctly. Parallel running is likely to be the most expensive as it involves doing the work twice for a period of time. However, it is the safest. If there are any bugs in the new system, you can always go back to the old system while the problems are corrected.
Pilot changeover
Changing over in a small part of the company to start with. Only when the system is deemed satisfactory will it be rolled out to the rest of the organisation. A supermarket introducing a new 'self-scanning' system might choose to introduce it in two or three stores at first. This is a pilot changeover.