12.1.2 Universal binaries on Macintosh

The supplied LispWorks (64-bit) for Macintosh images are now universal binaries which run the correct native architecture on PowerPC and Intel-based Macintosh computers by default. This was already true for LispWorks 5.0 (32-bit) for Macintosh but was not possible at the time of the initial LispWorks 5.0 (64-bit) for Macintosh release.

A running Lisp image only supports one architecture, chosen when the image was started. On a PowerPC based Macintosh, this is always the PowerPC architecture. On an Intel-based Macintosh, for 32-bit LispWorks it can be either the native Intel architecture or the PowerPC architecture (using Rosetta), while for 64-bit LispWorks it is always the Intel architecture.

Functions such as save-image and deliver create an image containing only the running architecture and functions that operate on fasl files such as compile-file and load only support the running architecture.

LispWorks Release Notes and Installation Guide - 18 Mar 2008