What is a "LISP machine"? More specifically,
(1) is this a brand name, and if so can you give some details about
the machine?
(2) is this simply a generic term for a machine that runs LISP?
(3) is it a generic term for something more than (2)?
(4) what are the advantages over any other machine that runs LISP?
(5) will it run anything other than LISP and what sort of
user-interface or operating system does it use?
(6) if it's more than "a machine that runs LISP", then can you
suggest where I might find a supplier? U.S. supplier would be fine.
MARK R DIAMOND
> What is a "LISP machine"? More specifically,
A Lisp machine is a computer which has been optimized to run lisp
efficiently and provide a good environment for programming in it.
These optimizations occur by these features:
1) Hardware Type checking - Since most lisps support untyped variables,
it is necessary to check the type of variables at run time. By
including type bits in the cons cell, it is possible to use hardware
to check before an instruction is executed.
2) Hardware Garbage Collection - The use of cons cells often creates
memory fragmentation; to reclaim unused memory, it is necessary to
do garbage collection. Lisp machines have hardware which does the
garbage collection with the minimum of interference to the operation
of running programs.
3) Fast function calls - since every lisp program is a function composed
of other functions, a lot more function calls occur in lisp programs
than in other programming languages. Additionally, a dependence on
such programming techniques as recursion also increases function calls.
Therefore, lisp machine designers have added features which make
function calling more efficient.
4) Efficient Representation of Lists - The representation of lists
can take up a lot of memory and take a long time to access a
list. Lisp machine designers use a number of techniques to speed
up access to lists and store them efficiently.
5) System Software - Since lisp programs can be quite large and have
a number of unique requirements, the designers of lisp machines have
created integrated programming environments which simplify the
writing of lisp programs and the management of lisp projects.
> if it's more than "a machine that runs LISP", then can you
> suggest where I might find a supplier? U.S. supplier would be fine.
Texas Instruments makes a card that fits into a Mac II based on their
Explorer lisp microprocessor. Contact:
Texas Instruments Incorporated
Data Systems Group
P.O. Box 181153 DSG-230
Austin Texas 78718
For references, see:
"Anatomy of a Lisp Machine" by Paul Graham
AI Expert, December 1988
"The Architecture of Lisp Machines" by Pleszkun and Thazhuthaveetil
IEEE Computer, March 1987
"A Lisp Machine Profile: Symbolics 3650" by Ditzel, Schuler and Thomas
AI Expert, January 1987