| 摘要 |
PURPOSE:To transmit the announcement message from the head at all time, by selecting the output of a plurality of counters in time division and reading out a digital signal through the provision of the address to an ROM. CONSTITUTION:An address selector ASEL selects the output of counters CTR1- CTRn by taking the output of the counter CRT0 as a gate signal and this selected CTRi output is the address signal ADR of an ROM. The data DATA of the output of the ROM corresponding to the address ADR given to the ROM is inputted to a time division channel via the selection circuit SEL. When the value of the counter CTRi starting count-up at the start signal CTLi coincides with the value of the message length timer MLT, the message is repeated by returning the output of the counter CTRi to zero. |
