Processor and byte order conversion method

In a processor provided with a CPU, a plurality of peripheral circuits, and a byte order conversion circuit provided between the CPU and the plurality of peripheral circuits, when a peripheral circuit explains a write value as a multi-byte value, it is prevented that the write value is explained as a value different from a value desired by a creator of software, thereby making the creation of the software easier. The byte order conversion circuit has a table indicating a relationship between an address and a category of a connection destination, and controls each of the data conversion circuit and the byte enable conversion circuit in the byte order conversion circuit by using category information extracted from the table using an address of an access destination. 提供如下的手段：在具备CPU、多个周边电路、以及设在CPU与多个周边电路之间的字节序转换电路的处理器中，在周边电路将写入值作为多字节的值进行了解释的情况下防止将其解释为与软件的创建者想要的值不同的值，使软件的创建更容易。字节序转换电路具有表示地址和连接目的地的类别的关系的表，利用使用访问目的地的地址从表取出的类别信息，分别控制字节序转换电路内的数据转换电路和字节使能转换电路。