Even as the role of the E-economy continues to expand, a majority of mission-critical data at large enterprises continues to reside on IBM mainframe computers - the System 390 (S/390) family. In addition, many branch offices and other remote locations in large enterprises and small-and mid-sized enterprises use IBM Application System 400 (AS/400)TM mid-range computers for their applications. PCs and workstations typically use a terminal-emulation program to access data residing on S/390 and AS/400 systems.

This paper compares the cost of traditional terminal-emulation solutions for accessing S/390 and AS/400 with emerging thin-client "Web-to-host" solutions. The latter can reduce the total cost of ownership (TCO) substantially - by as much as 60% in most cases.

This paper provides an overview of what is meant by "host access" and "terminal emulation" for the purpose of this TCO comparison. The overview is followed by a summary of the cost analysis model and TCO elements used as the foundation of The Tolly Group's conclusions. Finally, this paper provides information on the TCO of traditional "thick-client" emulation and "thin-client" Web-to-host solutions.