You can check the OpenBSD ksh man page which special characters are supported in the
PS1 prompt. Search for 'PS1' to find find them.
RE: Logo
A couple of weeks I was reading Seymour Papert's book 'Mindstorms' about the idea's about Logo, and the influence of Piaget's ideas on his theory how children/humans learn.
I bought a Windows 3..1 Logo implementation for my daughter when she was young, but at that time she wasn't too interested. Now she studies electrical engineering and develops web apps in PHP as a side-line job. So you never know if it had any influence