Abstract: A printer 10 provided with communication section 11 for obtaining print information necessary to print, from plural host devices 30 through transmission route 50, is characterized by comprising; a host ID getter 12 to get host ID able to distinguish host device which outputted said print information from other host device, with using the print information itself obtained; a trouble detector 14 able to detect trouble with judging whether printing based on said print information is possible or not; a presenter 16 to present said host ID obtained by said host ID getter 12 when printing was not judged possible by said trouble detector 14.

Abstract: A printing medium has means for storing electronic data. The means includes an input-output unit, a first memory, a second memory, a comparison unit, and an access controller. The second memory stores data for confirming the validity of the information printed on the printing medium. The first memory stores data for controlling access to the second memory. In particular, write access to the second memory is denied unless the accessing party also submits comparison data that compare correctly with the data stored in the first memory. This protocol prevents the facile creation of counterfeit copies.

Abstract: A printing medium has means for storing electronic data. The means includes an input-output unit, a first memory, a second memory, a comparison unit, and an access controller. The second memory stores data for confirming the validity of the information printed on the printing medium. The first memory stores data for controlling access to the second memory. In particular, write access to the second memory is denied unless the accessing party also submits comparison data that compare correctly with the data stored in the first memory. This protocol prevents the facile creation of counterfeit copies.

Abstract: A printer 10 provided with communication section 11 for obtaining print information necessary to print, from plural host devices 30 through transmission route 50, is characterized by comprising; a host ID getter 12 to get host ID able to distinguish host device which outputted said print information from other host device, with using the print information itself obtained; a trouble detector 14 able to detect trouble with judging whether printing based on said print information is possible or not; a presenter 16 to present said host ID obtained by said host ID getter 12 when printing was not judged possible by said trouble detector 14.