OPERATION MODE CONTROL CIRCUIT OF MICROCOMPUTER, AND ITS USING METHOD IN MICROCOMPUTER

摘要

PURPOSE:To increase an operation mode without providing a complicated external circuit by providing the first and the second terminals for indicating the operation mode, using the former as a bi-directional terminal for outputting an input and a clock signal, and using the latter as an input exclusive terminal. CONSTITUTION:Terminals 26, 27 are terminals for designating an operation mode. When a clock pulse CPO is an H level, an output of a gate 28 becomes an L level, a P channel MOS transistor 29 turns on, an N channel MOS transistor 30 turns off, and an H level is outputted to the terminal 26. Accordingly, when the clock pulse CPO falls, an input x1 is latched by an FF31 and an output y1 becomes an H level. In this case, the terminal 27 is pulled down, and as for an input x<2> of FFs 32, 33, an output y2 of the FF32 which latches x2 when the CPO falls becomes an L level, and an output y3 of the FF33 which latches x2 when a CP1 falls becomes an L level. By assigning these y1, y2 and y3 to the operation mode, an operation mode control decoder 8 generates a control signal required for a single chip mode.