| 摘要 |
<p>PURPOSE:To apply only one input buffer per one input terminal by pulling up the input of the input buffer to a CMOS level at the write mode of data by a PROM writer or the recognition mode of stored data. CONSTITUTION:When a microcomputer is operated by the data written in a PROM, a low level is inputted to a PROM power source terminal 5. When the low level is inputted to the terminal 5, a PROM writer mode signal 7 from a PROM writer mode detection circuit 6 is made to be a high level, a P channel transistor 4 is turned off, the input level of a signal inputted to an input terminal 1 is decided based on the CMOS level by the input buffer 2 and the output signal of the input buffer 2 is outputted to an output terminal 3. Thus, the signal 7 can be inputted to the gate of the transistor 4 constituting the pull-up resistance of each input circuit in common and each input circuit can be constituted only by the input buffer 2 and the pull-up resistance 4.</p> |
