A great many companies today are currently running numerous legacy (character-based or "green screen") applications on a variety of platforms (Mainframe, AS/400, Tandem, Stratus, etc.). Furthermore, there is an increasing trend toward integrating these systems with front-end GUI, Internet, and intranet applications, and using the Mainframe and AS/400 type computers for back office processing. Some companies are using AS/400s as Internet and Network servers. Most companies are opting to access their Mainframe (etc.) computers via Terminal Emulation from PC Workstations, rather than use "dumb terminals."
Many of these companies desire to automate their testing processes, but find the selection of a test tool that will meet all of their testing requirements difficult, at best. One tool may be better at testing legacy applications, while another is better at testing GUI applications, and still another is better at testing Internet/intranet applications.