Method for accessing microprocessor and microinstruction control type

Abstract

In a microprocessor, a microinstruction is used to control the microprocessor. The microprocessor includes: a decoder for decoding the STC instruction to obtain a decoded instruction and address data, the address data designating an address of a control space allocated to a plurality of registers in a general-purpose register group; an address register for temporarily storing the address data derived from the decoder; a microinstruction storage unit for previously storing a plurality of microinstructions and for outputting the microinstruction one by one in response to the decoded instruction; a microinstruction register for producing a control signal in response to the read microinstruction; a calculation unit for calculating the address data sotred in the address register means to obtain bit information of the address data for designating a specific register in response to the bit information derived from the calculation unit, while the general-purpose register group; and, a pointer register for temporarily storing the bit information to access the specific register in response to the bit information derived from the calculation unit, while the general-purpose register group is instructed in response to the control signal.