Patent ID: 7363622

Claim:
A centralized apparatus for downloading a program to a terminal apparatus, comprising: a storage medium that holds a latest version of a program composed of a plurality of software modules, the storage medium also holding a difference program generated in an apparatus for generating the difference program and composed of difference data corresponding to a difference between an old version of the program and the latest version of the program; a version acquirer that acquires, from the terminal apparatus, version information of the version of the program installed on the terminal apparatus; a data selector that selects the difference program when the acquired version information coincides with the old version of the program used to generate the difference program held in the storage medium, and that selects the latest version of the program when the acquired version information does not coincide with any version of the program used to generate the difference program; and a data transmitter that transmits the selected difference program or the selected latest version of the program to the terminal apparatus, wherein, when the data selector selects the difference program, the data transmitter transmits, with the difference program, an address that causes a first difference in contents between the old version of the program and the latest version of the program in comparing the programs and, when the data selector selects the latest version of the program, the data transmitter transmits, with the latest version of the program, a head address of the latest version of the program.