Patent GB-1049187-A (GB)
Title: Improvements in or relating to a message exchange system
IPC: H04L12/54
Filed: 1963-11-25
Abstract: 1,049,187. Exchange systems. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 25, 1963 [Dec. 7, 1962], No. 46382/63. Heading H4P. [Also in Division G4] A message exchange system for transferring messages received during random operating intervals on any of a plurality of input lines to any selected ones of a plurality of output lines in accordance with demands for the messages made on the output lines at random operating intervals, includes a store in series with each line. Referring to Fig. 17 (not shown), in a telephone exchange a data group on one of a number of incoming lines is routed to one of a number of outgoing lines with one of three priorities by a solenoid-operated switching matrix The data-group is stored in a queuing memory (see below) S1, S2 . . . or S64 until the matrix column wire relating to its required outgoing line and required priority is free when it is transferred into a queuing memory R65, R66 or &c. appropriate to its priority and outgoing line. It is passed from the queuing memory to the outgoing line when all previous data groups in the memory and all data groups in higher priority memories relating to the outgoing line (as determined by priority logic W1, W2 or &c., details in Fig. 18, not shown) have been transferred out. Each queuing memory consists of a chain of delay elements, each provided with gates to enable it to be bypassed without delay. In the first half of the chain, the data groups which may not on arrival at the memory be immediately following each other are shifted up so that they are. In the second half of the chain, the data groups are recirculated in separate delay elements until required at the output (on a first in, first out basis). The delay elements may be magnetic drums, discs or tapes or magnetostrictive, electromagnetic (lumped or distributed constant) or acoustic delay lines. Fig. 19 (not shown), shows a modification in which the queuing memories are replaced by a single queuing memory having 256 time-division " channels." Data groups on 64 incoming lines are time-division-multiplexed on to a single line and fed into the first 64 " channels " of the queuing memory. At the same time, the earliest data groups stored in these 64 " channels " are passed out of the queuing memory, delayed and passed back to the input of the queuing memory to be stored in the last 192 " channels " thereof. Each of the last 192 " channels " is assigned to one of three priorities of one of 64 outgoing lines and the delay is chosen so that each data group is stored in the " channel " appropriate to its destination and priority. As this re-storing is taking place the earliest data groups stored in the 192 " channels " are de-multiplexed on to the 64 outgoing lines, it being arranged that only the highest priority non-empty " channel " relating to the given outgoing line delivers a data group at a time. The delaying may be done by one or more tapped delay lines controlled by a control word inserted in front of the data group. It is mentioned that data group longer than the time interval allocated to one " channel " may be dealt with (and transferred from the queuing memory in one piece) provided the data group is preceded by a control word specifying its length or both preceded and followed by marker words. A magnetic core memory may alternatively be used for transfers from " channels " 1-64 to " channels " 65-256.