| 摘要 |
<p>PURPOSE:To decrease the number of the input/output terminal of LSI as well as to avoid the useless power consumption by using in common both the display signal output terminal and external memory control signal output terminal. CONSTITUTION:LSI1 of one chip contains the operational function, display function and external memory control function and also connected to key input part 2 and display part 3 via data bus D1. The key sampling signal to detect the key operation state of part 2 and the digit driving signal of part 3 use the same signal to perform each function. At the same time, the segment signal delivered from LSI1 according to the digit driving signal is supplied to each digit of part 3 via data bus D2. And three pieces among terminals of LSI1 used for the segment signal are used also for the chip enable signal output of two units of RAM41 and 42. In other words, the segment signal is supplied to condition circuit 13, and the common enable signal is delivered from circuit 13.</p> |
