To prevent data from being destroyed by providing a system for facilitating physical connection between a notebook computer and a host computer and for simultaneously and automatically performing data transfer without operating the notebook computer.

Both the host computer and the notebook computer are provided with a mechanism that easily connects the notebook computer to the host computer by providing many plug-in mechanisms for inserting the notebook computer into a rack type computer and a mechanism for starting data transfer by making it as a start for the notebook computer to be inserted into the plug-in mechanisms. It is also possible to provide an inexpensive solving means by simplifying the mechanism in such a manner that data to be transferred are limited to data that do not need data management and data synchronization.