PURPOSE: To perform not only the printing of the data from a host computer but also the printing original to a printing apparatus, by reading the printing data stored in the memory of the printing apparatus itself by a printing data supply part and taking out said data by the selection control from an input control part to transmit the same to an input buffer.

CONSTITUTION: An input control part 11 applies indication to a channel interface apparatus 1 or a printing data supply part 10 in order to input printing data to an input buffer 2. The printing data supply part 10 performs processing for inputting the printing data in a memory 9 to the input buffer 2 for storing said data temporarily. When the printing data is inputted to the input buffer 2, said printing data is converted to an internal code by a conversion table 3 to be stored in a page buffer 4. By providing the memory having the function storing the printing data other than the function processing the printing data to perform printing, the input control part 11 performing the selection of the printing data and the printing data supply part 10, the original printing data can be printed by a printing apparatus itself.