736,637. Automatic exchange systems. SIEMENS BROS., & CO., Ltd. June 25, 1954 [June 26, 1953], No. 17849/53. Class 40 (4). In an electrical impulse counter having a chain of binary counting units each having a normal condition and a registering condition, provision is made to skip certain numberregistering conditions. First embodiment, Fig. 1. A device for counting out impulses determined by a preliminary setting determined by a code signal on wires LW-LZ comprises four units A-D. Each unit such as A comprises an impulse input wire 1, a registering wire 2, a restoring wire 3, and primary and secondary counting relays PA, PB. Operation of contact m energizes PA which holds in series with QA when m opens. The beginning of the second impulse energizes release winding II to restore PA. The second make contact of each primary counting relay opens later than the first at release. QA holds during the second impulse over its winding II but releases at the end of the impulse so that the first unit A is now normal. The second impulse also brings the unit B to registering condition. Number-registering conditions 4 and 8 are skipped by high-speed relay N. At the beginning of the fourth impulse, A and B are already in registering condition and winding I of relay N pulls up quickly to prevent release of PA, so that only unit B restores while C assumes registering condition. The chain is then in position 5, position 4 having been skipped. Winding II of relay N similarly skips position 8. Counting-out. Temporary earth on one or two of wires LW-LZ according to an inverse binary code with 7 and 11 omitted sets the counter which then operates in the manner described above. When the last impulse is counted condition 15 is established with all units A-D energized so that end-of-cycle relay V operates quickly at the next closure of m to end sending. When m opens the counter restores to normal. Second embodiment, Figs. 2, 3. A registersender comprises six individual registers E-K and a sender. When a digit-key is operated according to the binary code with 4 and 8 omitted, battery over the appropriate wires LLW-LLZ operates the relevant combination of W-Z storage relays in register E, the operated relays locking up in series with control relay EE. EE transfers the registration in register E to register F. Release of the digit key clears the register E and control relay EE restores so that FF pulls up. The first digit is thus transferred through successive registers to K. Subsequent digits may be keyed while this is taking place and follow the first digit along the chain. When a digit reaches register K the registration is extended to counting units PPA-PPD, QQA-QQD and counting- out relay ST energizes over one or two of its four windings. ST energizes PS of an auxiliary binary counting unit. ST also energizes impulse-generating relay MM, releases the storage relays in register K and disconnects them from the signalling wires WL-ZL. PS operates slowly to restore KK and opens a short-circuit round impulse-transmitting contacts mm2. MM self-operates and self-releases, sending impulses to line and to the impulse counter until ST restores. The impulse counter counts subtractively skipping positions 11 and 7 by the use of contacts qqd1. In the example of a first digit of 7, i.e. a number registering position 8, relays QQD, PPD are initially energized. The first impulse then energizes PPB, PPC while PPD is released by the energization of its winding II. At the end of the impulse QQD falls back and QQB, QQC pull up. The second impulse energizes PPA and restores PPB and so on. The seventh impulse releases PPA, followed at the end of the impulse by QQA so that the counting units A-D are all normal. ST therefore falls back to operate QS in the auxiliary binary counting unit, which reenergizes ST through one or more strappings STR to set up a number on the counter appropriate to the length of the interdigital pause. ST releases PS in the auxiliary counting unit so that the impulses of the interdigital pause number are rendered ineffective by the shortcircuit through contacts ps3. At the end of the pause the next digit is transferred to the counter.