| 摘要 |
1,213,620. Digital transmission systems. SIEMENS A.G. 6 May, 1969 [7 May, 1968], No. 22932/69. Heading H4P. Received messages of various priorities are distributed to the appropriate receiver S1, S2 or S3 by the circuit shown. Each message consists of one or more n-bit words, the first word including a Start signal and a priority signal, and the last word including an End signal. A message of one priority can be interrupted by a message of higher priority. When a message ends the most recently interrupted message resumes. Thus, as shown, a first message consisting of words Z11- Z14 and having priority P3 is interrupted by message Z21-Z24 having priority P2, this message itself being interrupted by message Z3 having priority P3. Each received word is stored at R, and D1 determines whether a Start or End signal is present and sets bi-stables Ka, Ke accordingly. If a Start signal is present D2 examines the priority signal and sets bi-stable K1, K2 or K3 accordingly, the latter controlling unit V to pass the word from R to the receiver S1, S2 or S3 of appropriate priority. K1-K3 also control unit L which, when an End signal is received, resets that one of K1-K3 which represents the priority of the message just ended so that the next word received is passed by V to the appropriate receiver. Ka, Ke are reset whenever a word is read from R. |
