Flashcards for the topic

System development and Legacy Systems

Most organizations, at some stage in their development, require the introduction of a new IT system as well as the maintenance and eventual retirement of their current systems.
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Designing, developing, installing, and changing over to new IT systems is still an area that causes great problems for many organisations, and often results in failure and wasted money
The ability of the organisation to manage this change can determine the future viability of the organization.

Types of Development

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  • Off-the-shelf software, as its name suggests, is software that is widely available for general purchase from software vendors.
  • Custom / bespoke software is created specifically for a single organisation. Usually the organisation hires a soft- ware development company, but it may also have its own software developers in house

Businesses might employ bespoke software if it is more tailored to their needs than off-the-shelf software packages. At the larger end of the scale, corporations like NASA or Boeing contract software developers to create their software (it is obviously very difficult to walk into a shop and buy a shuttle control program off-the-shelf!).

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Development Tools

Software developers use a variety of programs to create new software. A text editor is used to enter the program’s source code, a compiler translates the source code into machine code, and debugging tools to help find and fix errors in the program they are creating. Often these tools are packaged together in an Integrated Development Environment (IDE).

Legacy systems

A legacy system is a computer system that is no longer available for purchase or is no longer supported by the manufacturer. A legacy system might be just a few years old, or it could be decades old. Often organisations continue to use legacy systems be- cause they are essential to their operation and there is no easily available replacement. Replacing a legacy system with a new one may be cost prohibitive, and with very old software, it may be extremely difficult to convert data from a legacy system to a new format. A 2011 report suggested that the US government spent 46% of its annual $36 billion IT budget on maintaining legacy systems
Legacy Fail


BBC Legacy systems: banks are likely to suffer more and more software failures

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Emulation and Virtual Machines

One solution to using legacy systems in a modern environment is to employ a virtual machine (VM), which creates a virtual ‘computer’ running inside a window, like a regular application program.

If the legacy system requires hardware which is significantly different from the host computer (for example, it requires a different processor or mainframe hardware), a virtual machine may not be enough, and a program called an emulator may be needed. An emulator is a software recreation of an entire system’s hardware including its processor and associated hardware. There may be a performance reduction.


Task 1
Research real examples of the role of IT professionals who maintain legacy or develop new IT systems. You can also interview anyone wish. Put together a brief report on your findings to submit next HL lesson.