446,454. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, Westminster, and PATTERSON, W. G., 59, Grove Park Road, Mottingham, and DIXON, R. G., 234, Avery Hill Road, Eltham, both in London. March 18, 1935, No. 8423. [Class 40 (iv)] In a code-translating register-controller, the registers for the numerical portion of the wanted designation, instead of forming part of the register-translator, are included in a circuit over which translators are taken into use, the translator being released immediately the routing digits have been sent. As described, the numerical registers are included in the A-digit switch toegether with sending and control switches for the transmission of the numerical digits. The out-pulsing loop, together with the impulse springs and associated control arrangements normally used in translators are also included in the circuits of the A-digit switch. The translator also has sending and control switches, and the sender is stepped synchronously with the numerical digit sender by the impulse springs in the A-digit switch, the stepping of the last-mentioned sender being necessary since, although it does not determine the routing digits, one of its banks (SS2) controls the out-pulsing loop. The commencement and termination of a routing digit are signalled back from the translator over a wiper of the A-digit switch. The units register is used to distribute the digits to the A-digit switch, translator and the numerical registers and special arrangements are provided for controlling the steering relay. In the case of zero calls, a translator is not taken into use, the routing digits being determined by crossconnections between the numerical digit sender and earlier contacts of its control switch. In the case of special service calls, TOL, TRU, &c. requiring no numerical digits, the A-digit switch is also released immediately the routing digits have been sent. Operation of A-digit switch and registration of digits. On seizure of the A-digit switch, relay A (left-hand winding) is operated over wire p and the polarizing winding of D is energized, relays B and BA pulling up and A holding over the in-pulsing wire pu when this is connected up at the first code selector. Magnet MM of the thousands register takes a step over MS1, MS2, US4 whereupon magnet UM of the units register takes a step over MS2 and US4. The original circuit of A is now open, dialling relay C is operated over US4, dial tone is connected to wirefr, and the impulse repeating circuit is connected over US6 to vertical magnet of the A-digit switch which steps in response to the first train, C being held over US1 during breaks. At the end of the train, C relapses since its original operating circuit over US4 is open at vertical off-normal contacts n so that UM steps US to contact 3. The rotary magnet operates over US2 and interacts with G, operated over wiper 3 by busy register-translators, until an idle one is found, whereupon H pulls up and locks over its low resistance winding and relay BC in the translator. Magnet UM operated over US4 steps switch US to contact 4 in which C pulls up and the impulse repeating circuit is connected over US6, ADS5 and CNSC2 to vertical magnet VC of the BC switch which takes the next train, the first impulse of which also operates UM to step US to contact 5 to provide a holding circuit for C during breaks. US6 in the impulse repeating circuit has a bridging wiper. The back stroke magnet CNMC of the translator control switch is operated over ADS6, US2, and the control switch takes a step when US steps to contact 6 on the relapse of C which thereupon re-operates. The next train is similarly repeated to the rotary magnet RC of the BC switch, US being stepped to contact 7 and subsequently when C relapses to 8. Magnet CNMC of the translator control switch also pulls up, but further operations of the translator will be described later. The thousands, hundreds and tens digits are repeated over US6 and pairs of contacts 8, 9 and so on to MM, CM and DM, the units digit being repeated to UM over the commoned contacts from 14 onwards in US6. There is no further pre-train operating circuit for C over US4. Transmission of routing digits. CNMC in the translator relapses, stepping CNSC to contact 3 when US leaves contact 7, and IG, Fig. 1, is connected up over CNS4(1) and US2. When impulse springs 11 open, IG pulls up and the sender magnets SM, SMC at the A-digit switch and translator respectively are pulsed, the circuit for SMC being over ADS5 and CNSC2. When sender SS reaches contact 3, out-pulsing springs are connected up over SS2 and transmission proceeds until SZC, Fig. 2, pulls up over SSC2, marked contact of BCS1, CNSC3, ADS1, CNS4 and US2, a parallel. circuit being also completed over ADS2 for stop relay SZ at the A-digit switch which shunts springs 12 and releases IG. Sender SS steps by self-interruption to contact 15, is pulsed by I1 to 19 and thence home by selfinterruption, while the translator sender SSC also goes home, both relays SZ and SZC being held over SS1 and SSC1 in parallel until both senders are home. The operation and release of relays SZ, SZC has stepped the control switches CNS and CNSC to contacts 2 and 4 respectively and the relapse of ZC restarts sending. Further routing digits determined by cross-connections between BCS2 ... 5 and SSC2 are transmitted until a wiper of BCS set to a contact connected to terminal dc is reached, whereupon DC, Fig. 1, pulls up over ADS4 and the previously described marking circuit and locks up. If there are six routing digits, DC pulls up over CNS2 on contact 7, there being no connection from BCS6 to dc. Relay DC releases H to release the registertranslator at which BC falls back and switches SSC, CNSC and BCS go home in turn, the testing in wire of the translator being open until offnormal contacts nc of BCS are closed. To proceed with the transmission of the numerical digits, CNS is driven over CNS2 to contact 7 if it is not already there due to the transmission of six routing trains. If or when the hundreds digit has been received, IG is connected up over CNS4 and wiper CS2 of the hundreds digit to initiate the transmission of the thousands digit marked in SS3 over MS3 and CNS3. The digit is terminated by the operation of SZ. The circuit operations of Fig. 1 during the sending of numerical digits are similar to its operations during the sending of the routing trains, the banks CS3, DS3, US3 of the registers being connected up in turn by CNS. After the transmission of the units digit, CNS steps to contact 11 whereupon CO operates over CNS3, locks up, opens the circuit of IG and opens the p wire which results in release of the A-digit switch by the first code selector. Relays A, B, BA fall back, but CO holds over its left-hand winding and off-normal contacts n. When the sender SS reaches home after transmission of the units digit, ground over wiper SS4 homes'CNS, DS, CS, MS, US in turn and the last-mentioned switch operates release magnet Z of ADS, CO thereupon falling back. All translators busy. Last contacts of the levels of ADS in banks 3 and 2 are connected to battery and busy signal respectively so that when the switch reaches these contacts and operates contacts s, H pulls up and the busy signal is sent back over fr to the first code selector which repeats it to the calling party. Contacts s3 prevent further operation of C so that any subsequent impulse trains are not repeated and the circuits remain in the present condition until the calling party releases. Zero calls. In response to the single digit O, the A-digit switch steps to the last contacts of the tenth level to which the busy signal is not connected. H pulls up and as US is on contact 4, DC operates over ADS4 and US2. Relay H thereupon relapses and sending starts as previously described, but the routing digits are now sent out as determined by cross-connections between the previously unused first five positions of CNS3 and frame CF to SS3, the self-stepping circuit of CNM being open at s1. The cut-off relay CO is operated over CNS3 in position 6 or over a previous position connected to dco according to the number of trains required. Other types of call. If the call is to a manual exchange, the routing digits are sent out as before, but when the junction to manual is taken into use, current reversal is sent back to operate D and disable IG to prevent transmission of numerical digits until a coder is available. In the case of a special service call, e.g. TOL, not requiring numerical digits, it is necessary to release the A-digit switch immediately after the routing trains have been sent. For this purpose, the next wiper of the BC switch is standing on a contact connected to dcoc so that COC is operated and the translator released. H, Fig. 1, relapses and as US is on contact 8, CO pulls up and releases the A-digit switch as before. Irregular operation. If a spare code is dialled, the senders step, but as there is no marking over the BC switch, M, Fig. 1, pulls up over SS5 and contact 14 and locks up, SZ being operated when SS3 reaches the directly grounded contact 22 so that the forced release wire fr is grounded to bring about the release of the first code selector. The digit 1 is not used for the A-digit and if it is dialled, post springs np are operated on the first level so that UM does not step on the relapse of C, but the release magnet Z is operated over US4. If no digits are dialled or an undue delay between digits occurs, TP will have been operated by a pulse on SP and locked up so that the next pulse over ZP operates M. If a digit has not been dialled, the forced release wire fr is grounded to release the first code selector. If dialling has occurred, H or DC will have been operated and M opens the loop to step the first code selector to the first level from which a tone signal is given. Relay IG operates and ineffective sending starts. The