Q:

I'm reading SICP and trying to follow along, but why do the Lisp interpreters I find online fail with the DEFINE keyword?

This is the book...
http://mitpress.mit.edu/sicp/full-text/book/book.html
Any idea which interpreter I should use to work with the code presented here?
So far I have tried a few online and download Lisp interpreters and all I get is errors when I try to use DEFINE.
Example:
From this section: http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-10.html#%_sec_1.1
Put in here: http://www.ugcs.caltech.edu/~rona/tlisp/
> (define (square x) (* x x))
*** EVAL Error: Function 'DEFINE' is not defined. ***

Also tried with 'lispbox' with similar results.
Ah HA: http://sisc-scheme.org/sisc-online.php works, thanks for the tip blabla999, will accept answer soon.
Upon further research: Scheme != Common Lisp

A:

probably because:
(EQ Scheme CommonLisp) -> #f
and also:
(EQ Scheme ManyOtherLisps) -> #f
try a real scheme (I recommand plt, which has been renamed to Racket, recently).
(Or write your own - see http://www.avc-cvut.cz/avc.php?id=9769)

