| 摘要 |
<p>PURPOSE: To attain miniaturization by providing some threshold values for a cell storing quantity in a buffer and controlling the read-out speed of a reading control circuit corresponding to whether the quantity is over the threshold values or not so as to reduce the too much and too little capacity of the buffer. CONSTITUTION: The threshold values (Th1 to Th3 ) are provided for the cell storing quantity Q of buffer RAM 11 so that a control part 15 detects the present quantity Q from the difference between writing and reading addresses by means of reading counters 12 and 13 . Next, the control part 15 judges comparing whether the quantity Q is over Th3 or not so as to read a cell by the reading period T4 of a reading period generation circuit 14 when quantity Q is over Th3 and to continuously judge whether quantity Q is over Th2 or not when the quantity Q is not over Th3 . Corresponding to this result, the control part 15 reads the cell by a reading period T3 when the quantity Q is over Th1 and next, when the quantity Q is not over Th1 , reads the cell by reading periods T2 by judging whether the quantity Q is over Th1 or not. Thereby, the too much and too little capacity of RAM 11 is reduced so that excessive quantity Q is unnecessitated, miniaturization is possible and scrapping cell is reduced.</p> |
