We have found personal computers, even of modest power, to be a useful and economical extension of the computing power of workstations and supercomputers. In part, the editors, word processors, drawing programs, and user interfaces on the PCs are often more advanced than those on scientific machines. Further, it is also possible to use an inexpensive PC as a graphics terminal to a larger computer-often at a much lower cost than a dedicated terminal-and then combine the better features of both systems. For example, as discussed in Chapter 2, Workstation Setup and Use, and Chapter 3, Computer-Computer Interactions, you can make diskettes on the PCs containing ASCII copies of your workstation files and then transport them to another location, mail them around the world, use a local PC to work on them, or transfer them to another machine.
To use a personal computer as a terminal to another computer requires two basic things: a connection to the other computer and a program which permits your PC to emulate the behavioral characteristics of one of the standard terminals. The connection can be one of several possibilities, with the type of connection influencing the type of emulation. One type of connection is through the modem port or serial port on the PC; if connected to an actual modem, it permits you to use the phone lines to communicate with other computers. If the computer you want to communicate with is nearby, you can run a serial (RS232) cable from the serial port on your PC to a serial port on the big computer. Another type of connection is through an ethernet port to a TCP/IP network. This requires you to have an ethernet card in your computer to send and receive data with the correct protocol. Finally, we mention that there are systems that connect PCs together (such as Apple Talk, Tops, PhoneNet, LocalTalk) which are useful in their own right, but also may contain a gateway box or connection to TCP/IP networks. These often open up a wider world to many PC users.
The software or terminal emulation program you need depends on what type of connection you have. For a PC running DOS with a simple serial connection, the common-domain emulator program kermit (which also contains the kermit file transfer protocol) will probably be adequate as a text terminal. However, it may not be adequate as a graphics terminal emulator for your application.
For a Macintosh on a serial connection, we recommend the commercial product Versa Term Pro by Synergy. It is also excellent for a TCP/IP connection, although in the latter case you can use the free NCSA telnet. You can use Versa Term Pro for text and color graphics by emulating DEC and Tektronix terminals, with automatic switching between them. In fact, we find that a good combination to use is Versaterm Pro on your Mac and Gnuplot on your workstation; since Versaterm automatically emulates a Tektronix display, you can do your plotting over the network without the need to run X Windows on your PC.
If your PC has a connection to the TCP/IP networks, either directly or through a gateway, then we recommend the two programs NCSA telnet for the IBM PC, and NCSA telnet for the Macintosh. These programs can be obtained free over the network from the National Center for Supercomputing Applications or for a nominal charge through the mails (see § ). The telnet from NCSA lets you have simultaneous connections (multiple windows) to any number of computers on the network, and to transfer files rapidly with ftp. Further, you can emulate color graphics terminals and switch to text terminals including DEC VT 102 and Tektronix 4014.
We have found the use of PCs as adjoints to workstations invaluable in our work. By using a PC as a terminal to the workstation, we can look at some graphics output in a Tektronix window on the PC. We then can import that image into the PC and use the drawing program on the PC to polish up the graph for publication.