Common Lisp the Language, 2nd Edition
Common Lisp is intended to meet these goals:
Common Lisp intentionally excludes features that cannot be implemented easily on a broad class of machines. On the one hand, features that are difficult or expensive to implement on hardware without special microcode are avoided or provided in a more abstract and efficiently implementable form. (Examples of this are the invisible forwarding pointers and locatives of Zetalisp. Some of the problems that they solve are addressed in different ways in Common Lisp.) On the other hand, features that are useful only on certain ``ordinary'' or ``commercial'' processors are avoided or made optional. (An example of this is the type declaration facility, which is useful in some implementations and completely ignored in others. Type declarations are completely optional and for correct programs affect only efficiency, not semantics.) Common Lisp is designed to make it easy to write programs that depend as little as possible on machine-specific characteristics, such as word length, while allowing some variety of implementation techniques.
The goals of Common Lisp are thus very close to those of Standard Lisp  and Portable Standard Lisp . Common Lisp differs from Standard Lisp primarily in incorporating more features, including a richer and more complicated set of data types and more complex control structures.
This book is intended to be a language specification rather than an implementation specification (although implementation notes are scattered throughout the text). It defines a set of standard language concepts and constructs that may be used for communication of data structures and algorithms in the Common Lisp dialect. This set of concepts and constructs is sometimes referred to as the ``core Common Lisp language'' because it contains conceptually necessary or important features. It is not necessarily implementationally minimal. While many features could be defined in terms of others by writing Lisp code, and indeed may be implemented that way, it was felt that these features should be conceptually primitive so that there might be agreement among all users as to their usage. (For example, bignums and rational numbers could be implemented as Lisp code given operations on fixnums. However, it is important to the conceptual integrity of the language that they be regarded by the user as primitive, and they are useful enough to warrant a standard definition.)
For the most part, this book defines a programming language, not a programming environment. A few interfaces are defined for invoking such standard programming tools as a compiler, an editor, a program trace facility, and a debugger, but very little is said about their nature or operation. It is expected that one or more extensive programming environments will be built using Common Lisp as a foundation, and will be documented separately.
There are now many implementations of Common Lisp, some programmed by research groups in universities and some by companies that sell them commercially, and a number of useful programming environments have indeed grown up around these implementations. What is more, all the goals stated above have been achieved, most notably that of portability. Moving large bodies of Lisp code from one computer to another is now routine.