| 摘要 |
<p>PURPOSE:To stabilize data output asynchronously by connecting a P- or N-type MOSFET according to the coding of a ROM is 'H' or 'L'. CONSTITUTION:Address signals An-A0 are decoded by a NOR4 and 'H' is outputted to one of signal lines RSm-RS0 while 'L' is outputted through an inverter 5. Those are coupled and when a data line 6 is held at 'L', the output of the NOR4 is connected to the gate of an N-FET7, whose source is grounded while the drain is connected to a data line 6; when the data line 6 is held at 'H', the output of the inverter 5 is connected to the gate of a P-FET8, whose source is held at a high potential while its drain is connected to the data line 6. Consequently, the NOR output is coupled with a power source and outputted stably through the P- or N-type MOSFET regardless of the output is at 'L' or 'H'. When addresses are changed, a selection signal line is selected according to the change to output data, thereby performing asynchronous operation.</p> |
