| 摘要 |
PURPOSE:To take out the internal bus signals to the external pins smaller than the number of objective signal lines by adding a signal switching mechanism to an integrated circuit IC, thereby dividing the internal bus signal having a large number of bits and switching these divided bus signals. CONSTITUTION:An internal bus 1 for the output of a computing element has the 32-bit width and an internal register 2 has the 16-bit width. A signal switch mechanism 3 performs the switching between the signals received from the bus 1 and the register 2. The signal received from the bus 1 has the 32-bit width and therefore divided into high-order 16 bits and low-order 16 bits. Therefore three systems of signals are switched by the mechanism 3 under such conditions. The switched signals can be taken out of an external pin 4 of an IC. Thus it is possible to check the bus 1 of the IC via the pin 4 required originally by the IC without extending a checking external pin. |
