To provide simple and inexpensive information processing system, information processor and information processing method, which do not require a complicated circuit and the memory of large capacity as much as possible, by preventing an overrun and executing desired printing.

Printing data transferred from a host computer 3000 to a printer 1500 are stored in a picture memory 24 and idle information on idle capacity is calculated while the capacity of stored data is monitored in a memory monitoring part 25 at any time. An idle information is informed to the host computer 3000 by a notice means 27. The host computer 3000 selects the resolution of data which is transferred next and data of prescribed selected resolution is transferred to the printer 1500 so as to execute printing.