Differences between PROLOG version 4 and versions 3 and 2
   ---------------------------------------------------------
There is a new version (version 4) as from 10 February 82 with the following
bugs fixed:
1) The bugs with name and =.. have been fixed.
2) The arithmetic bugs involving negative numbers have been fixed.
3) The debugging has been improved slightly. It is now possible to trace past
   cuts. Cuts are, in fact, now invisible to the tracing - like a few other
   evaluable predicates. Also the system no longer traces various obscure parts
   of the top level that used to appear before.
4) prompt(_,_) will not crash anymore if given a long atom. The atom can be any
   length, but note that the prompt actually used will be a truncated version
   of this if it too long. This seems to be an EMAS limitation. The current max
   length is 15.
5) The system now restores its event and interrupt handlers properly after
   returning from programs called through emas(_) or emas(_,_). This, for one
   thing, allows various editors other than the standard one to be used from
   within PROLOG (they used to mess things up so that you couldn't interrupt
   properly after using them).
6) The interrupt handling system has been improved somewhat, so that there
   should be very few of the "funny crashes". One way to make them happen
   still is to interrupt IMMEDIATELY after the command 'prolog'; if not
   immediate, then no silly crash ...
7) Exiting from PROLOG by typing ctrl_Y will no longer cause your next EMAS
   command to be ignored!
The EMAS PROLOG manual is available in VIEW form. Use the evaluable predicate
'um' (it stands for User Manual, of course!) to get at it. Outside PROLOG
you can view ECMI25.PROLOGDOCM