Patent GB-1410395-A (GB)
Title: Exchange systems
IPC: H04L12/52
Filed: 1973-05-10
Abstract: 1410395 Digital exchanges SIEMENS AG 10 May 1973 [2 June 1972] 22331/73 Heading H4P In a programme controlled exchange system in which signals on a plurality of line terminals are each assigned to effect the conversion of dialled characters, to one channel cell in a channel store of a character handling unit; in which characters are entered in bit-parallel fashion, such as is disclosed in Application No. 17751/73 an additional item of address information may be entered in a channel cell assigned to a particular connection line, the additional item is evaluated as a character recognition criterion and after being decoded serves to cause read out of a specific zone of a central character store in which are stored characters to be recognized. The characters in the channel cell which contains the respective additional item and signals in the zone of the character store read out by the additional item are passed to a comparator device. In the case of a positive comparison, a signal is issued to the programme store for evaluation. The additional address information may contain a first part which is conducted to a group number decoder and a second part conducted to a character number decoder, wherein as a result of the address determined by means of the decoding of the first part, a first specific zone within the character store containing the relevant individual character or a second specific zone within the character store containing the relevant character group is addressed and as a result of the address determined by decoding the second part, the relevant individual character or group is read out. In the modified arrangement it is not necessary for an entire character or character group to be stored but only the addresses for the character or group in the channel store. The character or group may be loaded by means of the programme or for example, manually. Further the character recognition means are relieved of load. In Fig. 1, all units co-operate with the central store SP through peripheral section MA which has incoming registers WER, BR, MLR and outgoing WAR, ADR. Registers WER, BR pass command data to control section USt data necessary for conversion. Polarity changes arriving via input lines may require to be intermediately stored in PWER before storage in a channel cell and processing by USt. Information to SP may be through transfer register MTR and word output register WAR, the addressing of individual zones being effected under control of counters BZ, MZ working into address register ADR. Character store ZVS also comparator ZVG may be reached from SP. Initially ZVS is loaded with characters to be recognized, i.e. zones VSZ are loaded with a programme each character being assigned a specific address combination ZEAD; for 15 storage positions VSZ1-VSZ15, circuits are used combination 000 specifying that no character recognition. At the beginning of a conversion, channel cells which are selected for assignment to a line are loaded additionally with a ZEAD address. If channel cell say KZn is selected and the ZEA address is not 0000, whenever the entire character is present indicating that a conversion has been concluded, this character is fed to comparator ZVG and address ZEAD is fed to decoder DEC which selects the appropriate cell character which is transferred to ZVG. In the case of correct comparison a signal is fed to SP where it is analysed by the programme. DEC and ZVG can form part of USt. Through the use of a short address, e.g. 4 bits this provides economy in the channel store. By the use of an address having a first section representing a group (GN) and a second section representing individual characters (ZN) led to group (GND) and character (ZND) number decoders respectively, with the character store being likewise divided into group (G1-n) and characters (EZ1-n) matrix, it is possible not only to recognize individual characters but groups also.