JPS6421656A - Read/write system for data - Google Patents

Abstract

PURPOSE:To easily realize a large scale integrated circuit by obtaining a common input output terminal and reduced a constituting element per register. CONSTITUTION:One instruction is issued from a processor 10 and by utilizing a time until the next instruction is issued, the shift processing of plural registers 1(1)-1(4), read data and write data are selected according to a read/write instruction 3 (in circle) from the processor 10. In the same way, even for data to be loaded on a data bus (a), which data of read data 1' (in circle) or write data 1 is selected is determined by controlling a state buffer 4 according to the read/write instruction 3 from the processor 10. Further, for a shift clock 4 (in circle) an address 2 (in circle) transmitted from the processor 10 through an address a' is converted in a decoder circuit 5 according to the output of the shift clock 4 (in circle). Thus, a common input output line is obtained between an address and data and the number of the input output terminals is cut down.