| 摘要 |
PURPOSE:To perform the test for the memory unit by applying the signals to the prescribed terminal during the reset state and thus securing free setting of the test mode. CONSTITUTION:Signal TEST is set to logic O while signal RESET is logic O, FF17 is set via NOR circuit 19-1. Then if signal RESET is set to ''1'' under these conditions, control part 16 features the test mode mask ROM3 damp. After this, part 16 features the application mode of the external order with signal TEST set to ''1''. At the same time, signal RESET is once set to ''0'' to set TEST to ''1''. And if RESET is set to ''1'' under these conditions, FF17 is reset via NOR circuit 19-2. In the mode of ROM damp, multiplexer 18 closes gates 36-39 and opens gates 40-43 to deliver the memory contents from input/output port 15. When the external order is applied, gates 20-27 are closed with gates 28-35 opened. And the decoding process is given through the multiplexer. |
