Patent ID: 7421527

Claim:
A first transmission apparatus provided in association with a second transmission apparatus, said first transmission apparatus receiving an interrupt signal from said second transmission apparatus, sending a command signal to said second transmission apparatus to allow data signal transmission from said second transmission apparatus to said first transmission apparatus, and receiving a data signal from said second transmission apparatus, said first transmission apparatus comprising: an input/output section having a command line and a data line which are configured for being connected to said second transmission apparatus, said command line sending a command signal from said first transmission apparatus to said second transmission apparatus, and said data line sending a data signal to or from said second transmission apparatus in response to said command signal; a data signal quiescent period detecting section, coupled to said input/out section, to detect signals along said command line and said data line, to detect whether or not said command signal transmitted along said command line is to permit transfer of a data signal, and to detect a data signal quiescent period which is any predetermined portion within a period from the end of a data signal transmitted in response to said command signal on said command line until the end of a next command signal to transfer a data signal on said data line; an interrupt signal detecting section, coupled to said input/output section, to detect an interrupt signal transmitted on the data line from the second transmission apparatus to said first transmission apparatus during said data signal quiescent period; and a CPU, coupled to said input/output section and said interrupt signal detecting section, to initiate an interrupt process in response to said interrupt signal.