Patent GB-902401-A (GB)
Title: Improvements in or relating to data processing equipment
Inventor: KAY ALEXANDER CECIL
IPC: H04Q3/545
Filed: 1957-12-23
Abstract: 902,401. Electrical calculating apparatus. STANDARD TELEPHONES & CABLES Ltd. Dec. 19, 1958 [Dec. 23, 1957], No. 39835/57. Class 106 (1). [Also in Group XXXIX] In a magnetic drum telephone metering system, a subscriber's metering total is read at each scan and passed to an adder which auto. matically adds one to the total. The modified total is supplied to a re-write gate which is opened only if a meter pulse has been detected on that subscriber's line. The magnetic drum has 16 storage tracks, 10 for use as meter storage tracks and 6 spare. Each track has 105 areas, 100 for subscribers, 2 for test purposes, and 3 vacant to provide time for switching from one track to another. Each subscriber's metering area has 24 elements. When a meter pulse occurs on a subscriber's line the related core in a matrix FS is set. These cores are scanned in synchronism with the scanning of the subscriber's meter records on the drum, a record being increased by 1 at the same time as the related core is reset. In a second embodiment the meter pulses are detected by an array of diodes and an entry is made temporarily in an intermediate store track of the drum. The meter pulses are then transferred to a permanent storage area in a manner similar to that of the first embodiment (Figs. 21-23, not shown). The meter records may be read-out automatically. All traffic relating to a P.B.X. is totalled by means of a library tape which ineludes an entry for each P.B.X. subscriber. This tape controls read-out causing the lines of a P.B.X. group to be selected one after another. Operation. A ferrite store FS has a matrix of 100 rows each of 10 cores. A meter pulse on a subscriber's line operates the associated core. Extraction of the pulse is controlled by an access selector AS which has a 10 Î 10 matrix of cores. Each row of this matrix is set by a pulse t0-t9 according to the track being scanned on the drum. The individual cores of the row are reset in turn by pulses 10w0-10w9 as each group of ten meter records is scanned. Each core as it is reset applies a reading pulse to the appropriate row of the storage matrix FS. The reading pulse restores any core in the row which has been operated by a meter pulse so producing an output pulse in the appropriate column wire to operate a bi-stable device in the related column circuit CT1-CT10. The outputs of the bi-stable devices are scanned sequentially under the control of pulses w0-w9 synchronously with the scanning of the meter records in a group of ten on the drum. If any bi-stable device has been set a pulse appears on lead L1 and is applied to re-write control gate RWGC, Fig. 2, causing the appropriate amended meter record to be written on the track as described later. The bi-stable device in CT1- CT10 is simultaneously restored. The subscribers' meter records are fed by reading heads through a transistor switching network TSN1 to a common reading amplifier CRA. The output from CRA is re-recorded and read out again (WA and RA) to provide a delay equivalent to the time difference between the reading and writing heads on the storage tracks. The output fed to an adder AD which adds 1. Thus as each subscriber's section arrives at the writing head, the existing meter record increased by 1 appears at the re-write gate RWG. If a meter pulse has occurred, as described above, RWGC opens gate RWG to enter the new total. If no meter pulse has occurred the existing record is unchanged. Split pulses. The first part of a split meter pulse is recorded. The second part initiates the same process but recording is prevented by entry of a " chalk-mark " A in a control element of the subscriber's storage area whenever addition is made. This mark is retained for 16 revolutions of the drum and prevents further addition during this time. Recording details. When a subscriber's meter total passes from 9999 to 0000 control means enter a " chalk-mark " B in another control element. At read-out this mark is removed. A " parity " element is marked with 1 if the number of 1's in the meter total is even, and with 0 if the total is odd. Including this element the number of 1's is therefore always odd and failure on this count energizes an alarm. Reading-out meter totals. The common read-out amplifier CRA also feeds read-out-gate ROG, Fig. 1. ROG is controlled by WM which, in bulk read-out, is controlled by the various counters to open at the appropriate times to read the meter record of the first subscriber on the first track. This record is passed into a staticiser and code translator SCT and is then recorded on tape at OD. Circuit AOG enters a spacing character and then WM is adjusted to read out the next meter record, and so on. AOG may also control entry of additional information such as time and date. A manual selector MS can control WM so as to display the meter record of a particular subscriber on a device ND. Segregation of P.B.X. records, Fig. 4. A library tape LT controls read-out of P.B.X. records. The tape carries the number of the different lines in the P.B.X. group and causes the appropriate totals to be recorded on tape at OD. The total for all the lines may be accumulated in ACC. If a meter has exceeded 9999 a " chalk-mark " B has been entered. The number of such marks in a P.B.X. group is counted during read-out and the marks are simultaneously cancelled. Continuous routine-testing. Ferrite store FS is tested by an extra row TR of ferrite cells which are all set by an artificial meter pulse generated by a test circuit RTC after all the rows have been scanned. The column circuits CT1-CT10 are tested in this manner. During the normal scanning cycle a check is made to ensure that all the column circuits are reset after each row of cells in the matrix has been dealt with. An extra section at the end of each storage track is scanned for testing the adder and rewrite gate. In each odd-numbered track is written 9999 and a meter pulse is simultated so that the circuits prepare to write 0000. A " chalk-mark " A is also pre-recorded in the test section and effectively blocks the writing amplifier CWA, so preventing writing of 0000. In even-numbered tracks the number 0000 is recorded and an attempt is made in 16 cycles to change this number to 1111 and then in one cycle -to 0000. This sequence tests operation of the addition circuits at maximum frequency. Failure of the apparatus to pass any test brings up an alarm and stops all operations. Specifications 902,403 and 902,404 are referred to.