The data processing device and electronic equipment of the present
invention perform pipeline control and include a fetch circuit which
fetches instruction codes of a plurality of instructions in instruction
queues. A prefix instruction decoder circuit performs a decode processing
only on a prefix instruction. The prefix instruction decoder circuit
receives the instruction code before decoding, judges whether or not the
instruction is a given prefix instruction, and causes a target
instruction to modify an information register to store information
necessary for decoding a target instruction when the instruction is the
given prefix instruction. A decoder circuit receives each of the
instruction codes of the instructions other than the prefix instruction
as a decode instruction and decodes the decode instruction. When the
decode instruction is a target instruction, the target instruction
modified by the prefix instruction is decoded based on the target
instruction modifying information.