WP-34S: Safely copy a graphics register's contents

[Dave Britten]

Now this is weird. If I run the program in unsigned mode, it actually corrupts itself. A couple of steps near the end of program memory change in a consistent manner, breaking the program. If I run it in 2's-complement mode, this doesn't occur. Let me transcribe and upload a copy of the code so you guys can see it. It's not too long...