Methods and apparatuses for securely operating shared host computers with portable apparatuses

The present invention provides methods and apparatuses that utilize a plurality of portable apparatuses to securely operate a plurality of host computers. Each portable apparatus including an operating system and a list of software applications is installed in a removable data storage medium. An authorization procedure is implemented before establishing a connected-state operation between a portable apparatus and a host computer. The host computer loads the operating system in the portable apparatus into its random access semiconductor memory (RAM) through the established connected-state operation.