Patent GB-1462306-A (GB)
Title: Communication method and network system
IPC: G06N3/10
Filed: 1974-01-28
Abstract: 1462306 Data storage systems; character recognition systems K E SAHIN 28 Jan 1974 3826/74 Headings G4R and G4C [Also in Division H4] A network comprises a regular array of modules each comprising a memory and a logic unit. Adjacent modules are connected by only one direct path, the path being able to carry messages in one direction only. A request message may be inserted into the network at any module and is propagated throughout the network to all other modules. If a module receives a request message, and provided this is the first time it has received it, it retransmits the message to all its outputs unless that module holds a response to that request. The module also stores the identity of the input or inputs on which it first received the request. If the module holds the response, that response is transmitted via an output determined by the stored identity. Each module receiving the response passes it on via an output determined by the respective stored identities, the response eventually arriving at the module at which the request message originally appeared. It is thus unnecessary for the identity or position of the request-initiating module or of the responseinitiating module to be known. For example, in the network shown in Fig. 2, suppose that a request is inserted at the centre module I. The request will pass to some of the adjacent modules via the outputs indicated by the filled arrow heads, and from these to other modules &c., as shown, so that each module receives the request at least once. At each module the identity of the input or inputs on which it first receives the request is stored. When the module containing the response pertinent to the request receives the request, e.g. the module V at the bottom left hand corner of the network, it transmits the response on an output 2 which depends on the stored identity or identities. When the response reaches the next module it is again forwarded on a particular output determined by the identities stored there. The path taken by the response in this example is shown by the broken arrow heads. The network may be used as an associative store in a computer system. The computer inserts a request message (tag word) at one module, or inserts two or more requests simultaneously at respective modules. The requests search all the modules associatively, and the response-holding modules provide response messages which pass to the appropriate requestinitiating modules over respective and reasonably direct paths. The network may also be used in a pattern recognition system. Consider, for example, the star network shown in Fig. 5, and suppose that each triangular group of three modules is connected to a corresponding shaped photocell. If a line, shown as a broken line, is imaged on the array of cells those modules C1-C9 shown by a heavy dot will be activated by an input from the cells. If a request is inserted into the network at the tip module of any star point the request will be received at two inputs simultaneously of each of the modules within the periphery of the network. When a module receives a request it passes a modified request on all its outputs if the module is activated or an unmodified request if it is not activated. However, if an unmodified request is received simultaneously on two inputs of an activated module the module also transmits a response on an output determined by which of the inputs first received a request. The response passes back to the star point module. By determining for each star point in turn the number and times of arrival of the responses from those of the activated modules that respond (e.g. from Cl, C4, C6, C9, shown circled, in response to a request from either star point RSP c  or LSP c ) certain characteristics of the pattern imaged on the photocells can be determined. For example, there is calculated for each star point a value V equal to the maximum difference of the response times divided by one less than the number of responses. The set of 6 values V so obtained is characteristic of the pattern and can be compared with reference sets of values to identify the pattern. It can be determined whether an edge of a pattern facing a starpoint is straight, convex, or concave by considering the time differences between successive responses at that starpoint, e.g. for a convex edge the differences increase after a series of equal differences. The angular orientation of a straight line, and its length, can be calculated from the values V, as can the curvature of a curved line.