Resending: Thank you very much for that! After RTFM, I found it there as well: <a href="http://docs.plt-scheme.org/reference/threads.html#%28part._.Creating_.Threads%29" target="_blank">http://docs.plt-scheme.org/reference/threads.html#(part._.Creating_.Threads)</a> <a href="http://list.cs.brown.edu/pipermail/plt-scheme/attachments/20090604/d3e3b060/gears.obj">http://list.cs.brown.edu/pipermail/plt-scheme/attachments/20090604/d3e3b060/gears.obj</a> is a version of gears.ss I tried to attach to my previous post. It allows you to do things like this at the REPL: (send c move-left) (send c run) Regards, Greg