Patent GB-915028-A (GB)
Title: Improvements in or relating to magnetic drum registers
Inventor: CLARK THOMAS HAROLD
IPC: H04M3/32
Filed: 1959-09-17
Abstract: 915,028. Automatic exchange equipment. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. Dec. 1, 1960 [Sept. 17, 1959], No. 31766/59. Class 40 (4). A number of register translators are simultaneously routine tested by a magnetic drum which holds a library of coded digits, such as would be dialled by a calling subscriber, and also holds the digit that should be given by a register translator if it responds correctly to a code, each register translator being associated with a particular register space on the drum. To permit each register space, and therefore each register controller, to be associated with all questions in the library of coded digits the registers and questions are contained in sections of equal length on different tracks of the drum, the register sections and question sections regenerating over different numbers of sections which are prime to each other. The register sections occur in six tracks, regeneration taking place over nine sections in each track but only eight sections of each track being used, provision being made thereby for simultaneously testing 48 register controllers. The library comprises 20 tracks, 10 of which contain coded digit questions and the other 10 of which contain the corresponding answers. Each library track regenerates over 13 sections. The register tracks are switched cyclically, one complete regeneration over nine sections being taken from each register track in turn for association with the library tracks. The particular library track with which any register is associated is determined by an address in the register which controls switching to that track. The register translators are connected to their respective register sections by means of relay sets and a scanning arrangement that may be as described in Specification 783,692. Arrangements are provided for an operator to write codes in any register or library section in the manner described in Specification 810,921. Once an address to a library section appears in a register section the associated code digits are transferred to the register section and are transmitted to the register translator associated with that section. The digits returned by the translator are entered in the same register section and are compared with the correct digits in the corresponding answer section in the library tracks. If the answer is correct the address of the next library section in sequence is written into the register section to conduct a further test with the next question. If the answer is not correct a fault meter associated with the register translator may be operated and further tests continue, or an alarm may be given and the test giving rise to a fault may be repeated so that the operator may set up the test data on a display. Repetition of a test is dependent on a so-called " camp-on " key which may also be used to test a register translator by means of a question keyed directly into a register section by the operator. Detailed description. Timing pulses.-Each track section comprises 20 blocks marked by the pulse cycle TB1 to TB20 and each block has six elements each capable of storing a bit and marked by the pulse cycle TA1 to TA6. Register sections are marked by the pulse cycle TCA1 to TCA9, the length of these cycles being marked by pulses TD1 to TD6, each of which characterizes a particular register track as it is switched in during the cyclic switching of tracks. Eight such cycles of the register tracks are marked by pulses TE1 to TE8 while each eight such cycles are further marked by the longest cycle of pulses TF1 to TF64. The library sections are marked by pulses TCB1 to TCB13. Register section layout.-This is given most conveniently by the following Table in which the columns are blocks and the rows are elements in each block. Test started, first question extracted.-By choice of a TCA and a TD pulse from the manual switches S1A, S2B, Fig. 7, together with the operation of a register track key KTR1, a pulse PSR is produced to mark a particular register section and, with a start key KST operated, testing of the associated register translator begins by setting toggle MAB, Fig. 1, at the coincidence of pulses TE1, TB1, TA2, provided the signal PPC is not present to indicate disconnection of the translator. With MAB set a start mark is written in element TA3 of block TB1 by the write 1 output SBS, the write 0 output being SAS. Should the start mark have been entered at an earlier revolution MAB is reset by the output SLS of the reading head at TA3 of TB1, read-out of 0 being indicated by SLS. During the first revolution with MAB set the address of the first library section and the first library track are marked by writing 1 in elements TA3 of the blocks TB18 and TB19. MAB is then reset in the last element of the register TA6 of TB20. The presence of a start mark produces a signal SLT, which is the read out signal SLS delayed by 4TD pulses, to set toggle MBB. Elements TA4, TA5 of TB1 are scanned to see if clearing or testing is in progress in which event MBB is promptly reset. If MBB remains set MCB is set at the end of the register and stays set for 11 blocks to cause a closed loop condition to be sent to the register controller from its associated relay set. A testing mark is made in elements TA5 of TB1 and a search mark is made in element TA1 of TB18 in response to toggle MDB which is set by the start mark. MDB is not allowed to mark testing or search if a clear down or testing mark exists in element TA4 or TA5 of TB1. A search is now conducted for the library section address by means of a toggle MEB and an auxiliary reading head placed one register section in advance and giving output SLP for a 1 and SLP for a 0. A similar auxiliary reading head of the selected library track gives output SLA for 1 and SLA for 0 and, together with the auxiliary register head, controls reset of the toggle MEB which is set by the search mark just ahead of the library section address in elements TA3 to TA6 of TB 18. If the addresses from the register and library section disagree MEB is reset and the search continues over further track cycles until the correct library section is found and MEB remains set when the normal reading heads scan the sections. With MEB set the search mark is erased by output SAS and the output SLL of the normal library reading head is gated in blocks TB3 to TB17 to write the coded digits of the library question into the register. MEB is then reset unless it is required by the next register section. Selection of wanted library track.-This is done by the toggles MAC to MGC of Fig. 2, toggles MDC to MGC staticizing the track number contained in elements TA3 to TA6 of block TB19 as they are read out and the states of toggles MEC, MFC, MGC being transferred to toggles MAC, MBC, MCC as elements TA6 of TB19 is read out. The condition of toggles MAC to MDC is translated to mark one of the leads T1 to T10 to mark the appropriate library track gating switches. Track selection may also be effected manually by a setting of the ganged switches S2C, S2D, S2E and S2F, which, when library track key KTL1 is thrown, sets up the toggles MAC to MDC during the end blocks of register sections TCA9 immediately before the spare register sections. Code digits sent to register-translator.-Along with the code digits busy marks are written into elements TA1 to TB3 to TB17, the first of which causes toggle MAD, Fig. 3, to set. So long as MAD is set and toggle MBD is not set the 0's encountered in elements TA3 to TA6 are changed to 1's until a 1 is reached when this is changed to 0 and MBD is set. By this means 1 is subtracted from the first digit and MDD is set to send an impulse to the register translator. A toggle MED is set to prevent subtraction from subsequent digits. Toggle MAD is similarly set by the busy mark during the next scan of the register section and the first digit is further reduced to transmit an impulse by way of MDD and this continues until all the elements TA3 to TA6 of TB3 contain 0's. When this state is reached all the elements will be changed to 1's by the final subtraction, MBD will not be set, and at element TA6 the read out of SLS will set toggle MCD to mark the end of a digit. Since MBD is not set MDD cannot be set and no impulse is sent. MED is set as before to guard the subsequent digits. It is now necessary to measure an interdigital pause and toggles MAD set and MBD not set produce output SBS to write an I.D.P. mark in element TA3 of TB20. Toggle MCD is normally reset by the absence of such an I.D.P. mark as detected by the auxiliary reading head one section in advance and so may be reset by other register sections before the next scan of the register being considered. During the next scan the I.D.P. mark sets MCD from the auxiliary reading head and causes a further I.D.P. mark to be written in element TA1 of TB2. Toggle MAD responds, as before, to the busy mark at the head of the digit column just transmitted and, with MCD set, MBD is not set and the elements TA3 to TA6 of TB3 are erased, erasure being halted by setting of MED to protect the subsequent digit. The I.D.P. mark in TA3 of TB20 is again made it being noted that both I.D.P. marks are made over the top of permanent erase circuits. At the next scan MBD is set by the I.D.P. mark in TA1 of TB2 and this erases the busy mark at the head of the first digit column. Setting of MED prevents this erasure extending over the other digit columns. The I.D.P. marks are not renewed so that MAD responds to the busy mark of the next digit block and proceeds with the next digit. This cycle proceeds over the fifteen digits registered. Code digits received from register-translator.- Since impulses from the translator may arrive quicker than the common equipment can clear one by one, arrangements are made whereby two impulses may be added to the digit blocks. The first digit from the translator relates to metering and occurs as a mark PIAN. All subsequent