Patent ID: 6948049

Claim:
A data processing system comprising: a special-purpose processing unit including dedicated circuit that is suited to special data processing; a general-purpose processing unit that is suited to general-purpose data processing; and a fetch unit for supplying, when an instruction code fetched from a code memory is a special-purpose instruction that specifies processing to be performed by the special-purpose processing unit, the special-purpose instruction to the special-purpose processing unit, and supplying, when the fetched instruction code is a general-purpose instruction that specifies processing by the general-purpose processing unit, the general-purpose instruction or a decoded data of the general-purpose instruction to the general-purpose processing unit; wherein the general-purpose processing unit is equipped with a first mode for operating based on a first instruction from the fetch unit and a second mode for operating based on a second instruction from the special-purpose processing unit; wherein the general-purpose processing unit includes an execution unit for executing data processing and a control unit for controlling the execution unit based on any of the first instruction and the second instruction; and wherein the control unit, on receiving a signal that requests the second mode prior to the second instruction from the special-purpose processing unit, ends processing in the execution unit that is based on a preceding first instruction, stores an address for fetching a general-purpose instruction that follows the first instruction, and outputs a signal for permitting the special-purpose processing unit to issue the second instruction.