CIRCUIT FOR CONTROLLING WRITE ON FIELD INSIDE EXTERNAL REGISTER AND CIRCUIT FOR CONTROLLING READ OF FIELD INSIDE EXTERNAL REGISTER

摘要

PURPOSE: To perform the write and the read of a field inside an external register by one instruction by responding to a field selecting signal and setting the field inside input data to the field corresponding to the field selecting signal inside the external register. ;CONSTITUTION: The input data to be set at the external register 2 are supplied through a data input circuit 61 to a field input selection circuit 81 and an address for setting the prescribed field inside the input data to the prescribed field inside the external register 2 is supplied to an address decoding circuit 4. The address decoding circuit 4 generates the field selecting signal and supplies it to the field input selection circuit 81. The field input selection circuit 81 sets the field inside the input data to the field inside the external register 2 corresponding to the field selecting signal. Thus, the input data can be set to the field of the external register by a simple instruction without being conscious of the other fields.;COPYRIGHT: (C)1994,JPO&Japio