There are N+1 tar files: one containing all of the source code, and one "binary" for each of the N supported processors. Click on "files", then "asmj", then "0.8". You should see a list of "tar.gz" files there.
The file named asmj-0.8-src.tar.gz
contains all of
the source code for the whole thing, including modules for all
supported processors.
There are also a bunch of files with names like
asmj-0.8-XXXX.tar.gz
.
These are the "binary" files; each is a compiled runnable assembler
for one of the various processors, and the XXXX tells you
which processor it is.
Each one contains a "jar" file that Java will run, and a "doc"
directory of documentation.
So, download one of those "binary" tar files, extract the jar file from it, and set your CLASSPATH to that. For example:
zcat asmj-0.8-6809.tar.gz |tar xvf - asmj-6809.jar
export CLASSPATH=$(pwd)/asmj-6809.jar
java Gui
Or maybe do real work with it:
java Asmj myprogram.asm
If you want to compile it yourself, you will want to download the source file. It contains N+1 directories: the top level directory holds the processor-independent files, and there is one subdirectory for each supported processor. When you compile it, class files will end up in each of those directories. Your classpath will need to include both the top-level directory AND one of the processor-specific subdirectories, or else you can copy all of those classe files together into a single directory as I did for the "binary" files above.