!TITLE Access to EMAS Prolog
!KEY
In order to use the interpreter it is necessary for you get access to  all  the
bits  of  the  system by adding the Prolog library to your search list with the
following EMAS command:

            Command: OPTION SEARCHDIR=CONLIB.PROLOG    

I  have  assumed  the  EMAS  "no  brackets"  convention  here;  see  the   EMAS
documentation  for  details.  This will only need to be done once, as EMAS will
remember it, If you are a student then this initial setting up  operation  will
probably  have  already been done for you, and you will not have to worry about
it (try the following and see).

Since Prolog makes syntactic use of the difference between upper and lower case
it is important that you have your terminal set up so  that  it  accepts  lower
case  in  the  normal  way.  This means, for a start, that you must be using an
upper and lower case terminal - and  not,  for  example,  an  upper  case  only
teletype.    It  is  possible  to use Prolog using upper case only (see section
1.15) but it is unnecessarily painful.  We shall assume both  upper  and  lower
case  throughout  this  manual.  Since EMAS does not always consider the use of
lower case to be the normal state of affairs, you may have to  tell  EMAS  that
that  is  what  you  want  before using Prolog.  This can be done with the EMAS
command:

            Command: SETMODE LOWER

More  usefully,  you  could havethis action occur automatically whenever you use
EMAS.  See the EMAS documentation, or ask someone who knows, for  more  details.
If  you  are a student you may find that all this is being done for you, so that
you don't have to bother about it.

To run Prolog type the EMAS command:

            Command: prolog

Prolog will then output a banner and prompt you for directives as follows:

            Emas Prolog             version n

            | ?-

There  will  be  a pause between the first line and the prompt while the system
loads itself. It is possible to type  ahead  during  this  period  if  you  get
impatient.
When  you run Prolog you can tell it to set your terminal properly (in case you
havn't done that yet), and you can  also  tell  it  to  start  by  restoring  a
save-state that you made earlier.  Save-states will be explained fully later.

            Command: PROLOG /L          (Set lower case)

            Command: PROLOG /V          (Set video and lower case)

            Command: prolog prog        (Restore "prog")

            Command: PROLOG PROG/L      (Restore "prog", set lower case)