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Path: utzoo!linus!decvax!harpo!utah-cs!sask!hardie
From: hardie@sask.UUCP (Peter Hardie)
Newsgroups: net.cog-eng
Subject: re: tops-20 command 'language'
Message-ID: <290@sask.UUCP>
Date: Sat, 20-Aug-83 10:43:38 EDT
Article-I.D.: sask.290
Posted: Sat Aug 20 10:43:38 1983
Date-Received: Sun, 21-Aug-83 07:11:10 EDT
Lines: 37

TOPS-20 command language (if you can call it a language) is NOT a particularly
good one to try to emulate. I dislike it for two major reasons ...
1. It requires very heavy support on the part of the processor to the extent
that the so-called 'front-end' processor in the DEC-20 actually passes
characters one by one to the backend with no processing of character deletes,
line deletes or other editing characters. This means that the backend has to
handle each and every character transmitted by the user as it is sent. The
front-end therefore becomes$!very expensive piece of wire.
The reason for this idiocy is that since only the backend knows the actual
command names and filenames (which can also be expanded with <ESC>) then the
backend has to see all the characters that you type. Admittedly, DEC 
implemented the front-end in about the worst possible way but it is still a
crummy idea.

2. It allows users to play around with commands that they don't understand.
Every year we have students here who play with the ? and escape keys
e.g.
t?
 [tops fills in with all commands known by exec beginning with T ]
talk ?
 [tops now tells them that the next arg is an octal line number]
talk 53
 [now they are interfering with a user on line 53 because even if the user has
  refused messages his terminal will still beep for a while]
  and of course if nothing interesting happens then they try talking to as
  many lines as they have time for until they find a user who has not refused
  links.  For those of you lucky enough never to have used a dec-20 the talk
  command is similar to 'write' and refusing links is essentially the same as
  'mesg n' .
They can also play around with the advise command and a huge number of others.
The real problem is that they can discover the names of commands and their
syntax without having to read a manual (they usually don't discover the help
command until two days before end of term :-) and thereby discover what the 
command actually does.

My opinion is that both menus and commands have their place but neither one
is really useful without a well-trained end-user.