Patent GB-1005480-A (GB)
Title: Apparatus for connecting electronic data processing systems with communication switching equipment
IPC: G06F3/16
Filed: 1964-02-26
Abstract: 1,005,480. Automatic exchange systems. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 26, 1964 [March 18, 1963], No. 7910/64. Heading H4K. Centralized data processing is performed by a digital computer for a number of remote users which have access to the computer over the voice frequency channels of a telephone exchange network, the computer being employed on a time shared basis and having access to the exchange over a number of lines any one of which can be selected for use by the computer in order automatically to set up a connection for data transmission to any desired remote user. As shown the computer 3 can transmit data to remote users by way of nine channels each of which has a data set DS-1 to DS-9 connected to an associated exchange line. Each data set has an associated automatic connecting unit ACU-1 to ACU-9 by means of which calls to remote users are established under supervision of a communication switching adapter 4 which receives instructions from the computer and regulates the supply of call establishing data provided by the computer. The computer sends dialling instructions as five bit serial codes preceded by a synchronizing bit. The first code in any instruction may indicate that the first idle exchange line should be seized; that a search is to be conducted for a free line in a group the first member of which is indicated by the next code; that a specific line is to be seized the identity of which is indicated by the next code; or that a connection is to be released as indicated by the next code. Calling units ACU-1 to ACU-9 are seized or marked busy by way of associated control units. When the first free calling unit is required for service the control units are examined in a chain circuit until the first free one is encountered. When the first free calling unit of a group is required the examination is started at a point in the chain circuit indicated by a code from the computer and extends to a unit specially wired to mark the end of the group. Where a specific line is demanded the line is selected on the basis of the identifying code. All codes from the computer are deserialized and set up for parallel access on a digit register. When a calling unit ACU is seized it replaces its idle marking to its control unit by a signal asking for the digits that are to be dialled into the exchange. The request is relayed back to the computer which forwards the digits to the digit register as four-bit codes, each digit being sent by the connecting unit before the next digit is requested from the computer. The last digit sent from the computer is followed by an end-ofnumber code to free the communication switching adapter 4 for further service. Should the remote user dialled prove inaccessible or busy the calling unit reverts a signal to the computer so that the call may be abandoned and tried again. Where a demand is made for a specific line that proves to be busy the computer may be instructed that it is not available or the line may be forcibly released to establish the new connection. A stepping register for the deserialization of codes received from the computer is described, Fig. 3a, not shown. A serial code generator is described for the presentation of call progress data to the computer, Fig. 3b, not shown. The logical functions necessary in a control unit for an automatic connecting unit are also described, Fig. 4, not shown.