Because CTC change their computer system from year to year, I can't include here instructions on how to log in. You should already know this from my demonstration, but if you don't, please ask. Note also that you need to log in in different ways on different machines. In particular, the method you use at CTC will not work in your college computer room, or in the Department. (This is unfortunate, and is the result of a long tradition of computer manufacturers refusing to standardise terminals and other equipment.) So if you want to work elsewhere than CTC, please ask me to show you how.
Let's assume then that you have already logged in and given your identification. You will then be talking to the VAX's operating system, the master control program which allocates the computer's ``attention'' between different programs and terminals. Each computer manufacturer has its own name for its operating system - the VAX one is called VMS.
VMS signals its presence by displaying a dollar prompt at the left hand end of the line. When you see this prompt, you can type a command, which you must terminate by hitting the RETURN key.
VMS accepts a variety of commands, many of which are to do with
creating, copying, printing, and deleting files. If you have used
another operating system, MS-DOS for instance, you'll be familiar with
the type of thing they do. However, we shall not use these commands
much. VMS also accepts commands which tell it to run programs, and we
shall use one of these, the eden command. So when you see a
$ prompt, type
edenand then hit the RETURN key. What this does is to tell VMS to start running Prolog, and to load into it the Eden microworld-simulator.
You should make sure that you are typing in lower case - that is, that you don't have the CAPS LOCK key on. Although VMS doesn't mind whether you use upper or lower case, Prolog does. Most letters in Prolog commands have to be lower-case, apart from the occasional use of upper-case for ``variables''.