Another example is the EICAR Standard AV Test Program<p><a href="http://mirror.href.com/thestarman/asm/eicar/eicarcom.html" rel="nofollow">http://mirror.href.com/thestarman/asm/eicar/eicarcom.html</a><p>It makes a few selfmodifications to run "unprintable" opcodes. (See Steps 12-14.)