| 摘要 |
<p>PURPOSE:To perform the switch of options via a ROM by outputting two types of data, i.e., the high and low data based on the data outputted from the ROM and selecting the function of an input port according to said two types of data. CONSTITUTION:For a microcomputer containing a ROM, the idle 7 bits are used among those higher rank 8 bits of a code of the ROM. The signals D1 of an EPROM1 are divided into the bits which are inputted in the timing of a 4phi-rise after reception of phi6-rise and the others which are supplied in the 4phi-timing to be used as 1st and 9th bit ROM data respectively. Such a circuit is used for signals D2 and the signal ER10 is used for input switch. A transistor TR3c conducts with a high signal with input of a rise waveform. While a TR3b conducts with a low signal with input of a fall waveform. Thus, the function of an input port can be selected.</p> |
