| 摘要 |
PURPOSE:To remove an initial defect easily by applying a control signal from the external to a gate circuit controlling the operations of respective internal constitutional elements and controlling the operation/unoperation. CONSTITUTION:In a normal operation mode, a test input terminal 1 is set to ''0''. At that time, the output of a program counter 2 is applied to a ROM3 as an address, a readout instruction is applied to an instruction decoder 5 through an internal bus 4 and a control circuit 6 operates respective internal circuits in accordance with the decoded result. When the test input terminal 1 is turned to logic ''1'', a program counter increment signal 7 is applied independently of the output of the control circuit 6 and all addresses in the ROM3 are accessed and a load signal 9 to a RAM address register 8 is also applied, so that the contents of a RAM10 are always rewritten. Similarly, the output of an I/O port 12 is always changed and an ALU16 executes arithmetic operation continuously. |
