| 摘要 |
1479774 Buffer store SIEMENS AG 8 Aug 1974 [26 Sept 1973] 35056/74 Heading G4C [Also in Division H4] A buffer store P is provided between a data terminal DEE transmitting data intermittently on line SDE, and a transmitting unit DUE which transmits data under control of a timing pulse train, each data bit from the terminal being read into a buffer stage identified by a write marker SM which is moved in response to receipt of data bits, and the contents of the buffer stage identified by read marker LM which is moved in response to the timing pulse train being read to the transmitting unit. The two markers, which may be ring counters marking successive ones of n lines, are advanced cyclically and arrangements are provided to prevent one marker overtaking the other. The buffer may be of a length sufficient to store a single multi-bit character including start and stop elements. If a single character is buffered the write marker SM is stopped after buffering of the stop element, i.e. the write marker now points to the start element. Read out from the buffer is then started and the read marker LM reads out successive stages until the stop element in stage KN is read out. The marker is then halted and, in the absence of further data from the terminal, the stop element will be read out repetitively, i.e. the pause between characters is lengthened. The read marker is held until a predetermined quantity of data is received from the terminal, e.g. until the write marker points to stage K3, the predetermined quantity being chosen to prevent the read marker overtaking the write marker given the most unfavourable speed difference. In the terminal is transmitting data faster than the transmitting unit can receive them the pauses between characters received from the terminal are used to continue transmission which thus occurs with shortened pauses between characters. The length of the buffer is chosen such that even with the largest possible difference between transmission rates the buffer can hold sufficient data to allow the randomly occurring pauses between characters to be lengthened or shortened to prevent one marker overtaking the other. |
