A legacy system is an existing system in operation within an organization. Often, legacy systems are based on old or inadequate technology. In large companies, many legacy systems run on host-based mainframe computers. Accounting software systems running on such computers are often written in COBOL, RPG, Basic, and PL1 (all are still in use)
Many large corporations replaced legacy systems just prior to the year 2000 in an effort to avoid a glitch known as the Y2K bug. One approach is to use screen scrapers, or front ware, which add modern, user friendly screen interfaces to legacy systems. There are limitations to this approach, because mainframe systems are not as efficient as newer technology.
Some companies are using new software to replace the old system. The new system is called an “EAI”. The new software is intended to be more user-friendly and efficient. The old system was designed to be a single, integrated system, but the new system will be more flexible.
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