A. Modern day PC users are used to having a system with large amounts of memory, disk and CPU power to run their applications. This is very different to UNIX and VMS environments where servers have all the memory, disks and CPU and users have "dumb" terminals which just send keystrokes to the server which in turn sends back screen updates.
There are a number of advantages with the UNIX/VMS approach. Most desktop computers are idle for most of the time with the CPU only 10% busy normally and a significant amount of memory spare, this is a waste of resources. A central server approach distributes resource's to sessions as needed, minimizing waste and ensuring resources are available when needed.
Installing applications and maintaining them on each desktop is very time consuming. A central server based install simplifies this significantly and lowers the Total Cost of Ownership (TCO).
Windows NT Terminal Server and Windows 2000 address this with client software for Windows 9x/NT and Windows for Workgroups machines that allow a window to be created which allows all processing and execution to be carried out on the server and the only task the local machine does is to pass back keyboard and mouse actions. The Terminal Server does all the computation and storage and passes back screen updates to the client.
Here you can see an example Terminal Server session in its own windows, with its own Start menu and taskbar. All applications in this window are being run on the terminal server. The information shown in Explorer is the Servers drives, not the local machine.
Obviously Windows NT/95 are operating systems of their own and it may seem pointless running terminal server client on these machines however it could be used for application management, install Office 97 on the Terminal Server and all clients use Office via the Terminal Server connection. Imagine running Office 97 on a Windows for Workgroups machine!
Communication is via RDP (Remote Desktop Protocol) which was designed by Microsoft.
Windows Terminal Server is based on Citrix's WinFrame product and Citrix provide a bolt-on, MetaFrame, which adds functionality to Terminal Server including support for DOS, OS/2, Unix, Java and much more. http://www.citrix.com