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From: royt@gatech.CSNET (Roy M Turner)
Newsgroups: net.ai
Subject: Re: Xerox Dandelion vs. Symbolics?
Message-ID: <4461@gatech.CSNET>
Date: Fri, 5-Sep-86 13:27:54 EDT
Article-I.D.: gatech.4461
Posted: Fri Sep  5 13:27:54 1986
Date-Received: Sat, 6-Sep-86 02:12:02 EDT
References: <25800003@siemens.UUCP>
Reply-To: royt@gatech.UUCP (Roy M Turner)
Organization: School of Information and Computer Science, Georgia Tech, Atlanta
Lines: 125

In article <25800003@siemens.UUCP> steve@siemens.UUCP writes:
>
.
.
.
>Every chance I
>get, I try to find out what a Symbolics/Zetalisp machine has that the
>Dandelion doesn't.  So far I have found only the following:
>
>1)  More powerful machine (but less power per dollar).
>
>2)  The standard of Commonlisp (only the past couple years).
>
>3)  People are ignorant of what the Dandelion has to offer.
>
>4)  Edit/debug cycle (and editor) very similar to old standard systems
>    such as Unix/C/Emacs or TOPS/Pascal/Emacs, and therefore easier
>    for beginners with previous experience.
.
.
.
>
>By the way, the Interlisp system on the Dandelion is about 5 megabytes
>(it varies depending on how much extra stuff you load in - I've never
>seen the system get as large as 6 Mb).  I hear that Zetalisp is 24 Mb.
>Is that true?  What is in it, that takes so much space?
>
>Steven J. Clark, Siemens Research and Technology Laboratory etc.
>{ihnp4!princeton | topaz}!siemens!steve
>

As a user of Symbolics Lisp machines, I will try to answer some of Steve's
comments.  We have had Symbolics machines here since before I started on my
degree two years ago; we recently were given thirteen Dandelions and two
DandyTigers by Xerox.  We use the Symbolics as our research machines, and the
Xerox machines for teaching AI.  

The Symbolics are more powerful, as Steve says, and quite possibly he is right
about the power per dollar being less for them than for Xerox; since the Xerox
machines were free to us, certainly he's right in our case! :-)  However, I
find the Dandelions abysmally slow for even small Lisp programs, on the order
of the ones we use in teaching (GPS (baby version), micro versions of SAM,
ELI, etc.).  To contemplate using them for the very large programs that we
develop as our research would be absurd--in my opinion, of course.

The "standard" of CommonLisp will (so Xerox tells us) be available for the
Dandelions soon...'course, they've been saying that for some time now :-).  So
the two machines may potentially be equal on that basis.  ZetaLisp is quite
close to CommonLisp (since it was one of the dialects Common Lisp is based
on), and also close to other major dialects of lisp--Maclisp, etc.--enough so
that I've never had any trouble switching between it and other lisps...with
one exception--you guessed it, Interlisp-D.  I realize that whatever you are
used to colors your thinking, but Lord, that lisp seems weird to me!  I mean,
comments that return values?? Gimme a break!

"People are ignorant of what the Dandelion has to offer."  I agree.  I'm one
of the people.  It has nice windows, much less complicated than Symbolics.
MasterScope is nice, too.  So is the structure editor, but that is not too
much of a problem to write on any other lisp machine, and is somewhat
confusing to learn (at least, that's the attitude I perceive in the students).
What the Dandelions *lack*, however, is any decent file manipulation
facilities (perhaps Common Lisp will fix this), a nice way of handling
processes, a communications package that works (IP-TCP, at least the copy we   
received, will trash the hard disk when our UNIX machines write to the
DandyTigers...the only thing that works even marginally well is when we send
files from the Symbolics!  Also, the translation portion of the communication
package leaves extraneous line-feeds, etc., lying about in the received file),
and A DECENT EDITOR! Which brings us to the next point made by Steve:

>4)  Edit/debug cycle (and editor) very similar to old standard systems
>    such as Unix/C/Emacs or TOPS/Pascal/Emacs, and therefore easier
>    for beginners with previous experience.

This is true.  However, it is also easier for experts and semi-experts (like
me) who may or may not have had prior experience with EMACS.  The Dandelions
offer a structure editor (and Tedit for text, but that doesn't count) and
that's it...if you want to edit something, you do it function by function.
Typically, what I do and what other people do on the Xerox machines is enter a
function in the lisp window, which makes it very difficult to keep track of
what you are doing in the function, and makes it mandatory that you enter
one function at a time.  Also, the function is immediately evaluated (the
defineq is, that is) and becomes part of your environment.  Heaven help you if
you didn't really mean to do it!  At least with ZMACS you can look over a file
before evaluating it.  Another gripe.  Many of our programs used property
lists, laboriously entered via the lisp interactor.  We do a makefile, and
voila--next time we load the file, the properties aren't there!  This has yet
to happen when something is put in an edit buffer and saved to disk on the
Symbolics.  Perhaps there is a way of editing on the Xerox machines that lends
itself to editing files (and multiple files at once), so that large programs
can be entered, edited, and documented (Interlisp-D comments are rather bad
for actually documenting code) easily...if so, I haven't found it.

Another point in Symbolics favor: reliability.  Granted, it sometimes isn't
that great for Symbolics, either, but we have had numerous, *numerous*
software and hardware failures on the Dandelions.  It's so bad that we have to
make sure the students save their functions to disk often, and have even had
to teach them how to copy sysouts and handle dead machines, since the machines
lock up from time to time with no apparent cause.  And the students must be
cautioned not to save their stuff only to one place, but to save it to the
file server, a floppy, and anywhere else they can, since floppies are trashed
quite often.  Dribble to the hard disk, forget to turn dribble off, there goes
the hard disk... Type (logout t) on the Dandelions to cause it not to save
your world, and there goes the Dandelion (it works on the DandyTigers).

About worlds and sysouts.  The Symbolics has a 24-30 meg world, something like
that.  This is *not* just lisp--it is your virtual memory, just as it is in a
Xerox Sysout.  The difference in size reflects the amount of space you have at
your disposal when creating conses, not the relative sizes of system software
(though I imagine ZetaLisp is larger than Interlisp-D).  You do not
necessarily save a world each time you logout from a Symbolics; you do on a
Dandelion...thus the next user who reboots a Symbolics gets a clean lisp,
whereas the next user of a Dandelion gets what was there before unless he
first copies another sysout and boots off of it.  It is, however, much harder
to save a world on the Symbolics than on the Xerox machines.

Well, I suppose I have sounded like a salesman for Symbolics.  I do not mean
to imply that Symbolics machines are without faults, nor do I mean to say that
Xerox machines are without merit!  We are quite grateful for the gift of the
Xerox machines; they are useful for teaching.  I just tried to present the
opinions of one Symbolics-jaded lisp machine user.

Back to the Symbolics machine now...I suppose that the DandyTiger beside it
will bite me! :-)

Roy