A portable information terminal capable of preventing programs from being illegally copied

摘要

A portable information terminal having an interface for connection to a master unit having a function to execute a program and having one or more control inputs for controlling operation of the portable information terminal and/or the master unit includes: illegal copying prevention means for periodically determining whether the information downloaded from the master unit is legitimate or not and if legitimate information has not been downloaded, making ineffective at least one or more of the control inputs. An entertainment system comprising an entertainment apparatus having a function to execute a program and a potable information terminal as described above which is detachably connected to the entertainment apparatus and having an interface for being electrically connected to the entertainment apparatus.