You can install LispWorks 5.1 in the same directory as previous versions of LispWorks such as LispWorks 5.0. This is because all the 5.1 files are stored in a subdirectory called
lib/5-1-0-0
.
You must recompile all your code with the LispWorks 5.1 compiler.
Binaries produced by
compile-file
in previous versions of LispWorks such as LispWorks 5.0 do not load into a LispWorks 5.1 image.