Yes, they are special, but...

["William D. Gooch" <ai.gooch@MCC.COM>]

    ...."highly specialized hardware"....

I've heard this idea bandied about enough that I suppose I should
understand it by now, but - sorry if I'm being dense - I still don't
know what it means.  The term "specialized," usually stated as in
opposition to "general-purpose," implies that there are things one
cannot do on a Symbolics machine which other hardware does support.
If you don't mind my asking, what are those things?  

Symbolics readily embraces software standards, usually before the other
vendors do.  They are now using an industry-standard bus architecture,
and providing coprocessor boards for other machines with unusually tight
software integration.  Certainly the Symbolics computers aren't 1as0 good
for some things as some other computers, but I don't know of any one
computer family that is ideal for every purpose.  I find the Symbolics
machines to be much better for a wide range of functionality than any
other computer systems I've ever come across.  Sure, there are always
tradeoffs, and to some extent you trade off performance for this broad
applicability (which might also be called "generality") in the current
Symbolics products.  But what exactly characterizes Symbolics systems as
"highly specialized?"