Unfortunately, CMD.exe doesn;t support ANSI.sys. It only works in 16-bit command.com "compatibility box" sessions, which are pathetic.

Using system 'cls'; works fine, but it just puzzles me why it bothers emitting chr(12), if nothing makes use of it. Still my best guess is that this is a remnent from teletype days that was intended to simulate clearing the screen when using a paper-teletype by throwing a new page.