GB1457285A - Apparatus providing communication in synchronous mode between any one of a plurality of terminal devices and a multiplex - Google Patents

Abstract

1457285 Data transmission; master and slave systems SIA INTERNATIONAL 29 Nov 1973 55328/73 Heading H4P An arrangement for synchronous connection of a plurality of terminals to a multiplexing channel 2 comprises an interface multiplier unit 1 connecting the channel to a plurality of first modems 8-10, each connected through a data channel to a second modem, e.g. 11 which serves a terminal, e.g. 5. The multiplexing channel has a receive data circuit and each first modem has a "receive data" circuit and a "carrier on" circuit whereby the multiplier unit has a logic means for effecting the product, e.g. AND operation of the "receive data" circuit and "carry on" circuits of the respective first modems. In Fig. 1, multiplier unit 1 is connected through a channel of multiplexer 3 to a computer 4. In use, the multiplier (a) transmits data from the computer to all terminals which decode its particular address, (b) recognizes which terminal is transmitting, one at a time, without decoding addresses and (c) switches, data to the computer together with associated clock signals. In a modification (Fig. 4, not shown) some terminals (e.g. 33, 34) may be connected directly to the interface multiplier, (la), also additional modems (31, 32) with an associated duplex or simplex channel may be connected therebetween. Details of logical arrangements are given in the Specification. Fig. 7 (also not shown) illustrates a buffer circuit to take up shift between individual clocks.