| 摘要 |
PURPOSE:To improve the removal efficiency of an initial fault by inputting a signal which is effective only at the time of burn-in to a circuit constituting an instruction changing the value of a program counter in an instruction decoder part. CONSTITUTION:When the voltage of a power source 1 is set to be five volts and 12 volts is impressed on a test terminal B, for example, a P-channel transistor 9 comes to an on-state and an N-channel transistor 10 is in the on-state. Thus, the output of an invertor 8 comes to '0' by setting a transistor size so that the input of the invertor 8 can be recognized as '1' when the P-channel transistor 9 is turned on, and an N-channel transistor 7 comes to an off-state. Namely, an N-channel transistor array 3 and an N-channel transistor 4 come to a detached state and a control signal A is set to be '0' as it is even if the instruction code of FF is inputted from ROM. Consequently, the instruction for changing the value of the program counter is not executed in a burn-in mode. Thus, burn-in is attained in a state where most circuits are operated. |
