Data processing method, and data processor and printer using data processing method

A printer which accesses a memory by using a CPU an a DMA controller, comprising:

• a CPU bus with an N-bit physical bus width shared by said CPU and said DMA controller;
• an input unit, arranged to receive as input print data from an external device;
• a detector that detects a request as to whether to execute a first mode in which said CPU accesses said memory via said CPU bus with an N1-bit width to handle said print data, or to execute a second mode in which said DMA controller accesses said memory via said CPU bus with an N2-bit width to handle the print data;
• a switching unit arranged to switch an exclusive access right for said CPU bus, depending on whether executing said first mode, or executing said second mode;
• and
• a printing unit arranged to receive said print data, to print on a print medium based on said print data,
• wherein N, N1 and N2 are respectively positive integers, N2 is greater than N1, and N is equal to or greater than N2.

A data processing apparatus for accessing a memory by a CPU and a DMA controller via a bus with an N-bit physical bus width, comprising:

• a first memory-accesser, that executes a first mode in which said CPU accesses said memory with an N1-bit width;
• a second memory-accesser, that executes a second mode in which said DMA controller DMA-accesses said memory with an N2-bit width;
• a detector, that detects a request as to whether to execute said first mode or said second mode;
• and
• a switching unit that, based on the detection by said detector, switches between execution of said first mode and that of said second mode, such that said CPU or said DMA controller which has an exclusive access right for said bus can execute memory access,
• wherein N, N1 and N2 are respectively positive integers, N2 is greater than N1, and N is equal or greater than N2.