Patent GB-810921-A (GB)
Title: Improvements in or relating to magnetic recorders for the storage of information in binary form
Inventor: MANN VICTOR EDMUND
IPC: H04Q3/42
Filed: 1955-03-21
Abstract: 810,921. Automatic exchange systems. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. Feb. 28, 1956 [DZarch 21, 1955], No. 8182/55. Class 40 (4). In a magnetic drum arrangement having " library tracks " carrying metering and routing information, the information is inserted or amended by writing in the amended information on an auxiliary track and then transferring the information from the auxiliary track to the library track in a single rotation of the drum. As shown, Fig. 1, the drum contains an address track AR, AW, capable of carrying all possible combinations of the A and B digits of exchange codes and " library tracks " LR1, LW1 ... LRN, LWN, one for each value of the C digit of the code. Each track comprises recording elements TX capable of receiving a binary digit, six such elements making up a TY section which is used for recording a single decimal digit (in binary forml. The TY sections are grouped in blocks of 14, divided into two sub-blocks TY1-TY7, TY8-TY14 each of which pertains to a different exchange code. A transfer track TR, TW has its reading and writing heads regenoratively coupled and separated by seven TY sections so that on the insertion of information into one sub-block of seven TY sections, the information is repeated in every other sub-block of the track. The auxiliary track in fact comprises two regeneratively coupled traces RR1, RW1, RR2, RW2 coupled in series. When information in a library track is to be amended, the information is run off the appropriate library track on to the regenerative tracks. The address of the information (i.e. the A and B digits) are fed into the transfer track and when coincidence is observed between the address on the transfer track and that on the address track a reference marking is inserted on the regenerative track serving to indicate where the amended information is to be fed in. Since coincidence can only be detected after the whole of the address has been read, it is arranged that the library information lags one sub-block behind the address. When the regenerative track contains the whole of the amended information it is fed into the appropriate library track over switch KYT by operation of key KWW. It will be noted that in the arrangements for reading the various tracks circuits are provided having two outputs (e.g. SLW, SLW) which are respectively energized according as a 1 or a 0 is read. Likewise, first and second input terminal SAW, SBW are provided for writing in a 0 or a 1 respectively and the second terminal overriding the first. The control of operations is effected by means of six bistable relays MAW ... MFW (not shown) which are operated and reset as described below. The transfer track may be that used by a register for extracting information for the drum. Keyboard control.-Changing or writing library information. The erase key KEW is first thrown, potential applied to lead KEL thereby causing potential on lead SAW to write 0 in all elements of the regenerative track RR1, RR2, RW1, RW2. With start key KSW in the normal condition however, lead KSL carries potential and lead SBW is energized during TX2 periods to write 1 in each TX2 element as reference signals. Key KSW in its normal position also restores bistable state relays MAW, MBW, MCW, MEW to this normal state. The copy key KCW is now thrown to earth lead KSL and energize lead KCL to operate relay MEW. The transfer track may be in use by a register. When it becomes free a 0 is inserted in element TX2, TY8, and the resulting output SLT at this instant operates relay MAW and also causes the insertion of a 1 in this element of the transfer track to busy it. This output is also used to reset the combination of relays LTS used for selection of the appropriate library track. The switch KYT is now operated manually to select the library track which is to be written into or amended. This causes potential to be applied to a coded combination of leads KY1 ... KY4 and this causes the code to be emitted in sequential form at instants TX3 ... TX6 to set the relay set LTS (by means not shown), thereby to select a library track say LRN, LWN. The information on this track is then fed via circuit SLL and lead SBW on to the regenerative track RR1, RR2; RW1, RW2. The restoration of the copy KCW with KSW still normal restores relays MAW, MEW. The transfer track has a timed release circuit which applies a cancel condition during the period TZ1. This however is over-ridden when MAW, MEW are operated. Thus with the MAW, MEW released the transfer track is released and may be used by a register. When the key KSW is moved to the left-hand or " library " position and the transfer track is free MAW operates and the track is busied as previously described, thereby terminating the insertion of 1's in the TX2 elements of the regenerative track and permitting a zero to be inserted in this track position TX2, TY8, TZ1, TW1 corresponding to the beginning of the address track. This had previously been overridden by potential on lead KSL energizing SBW at TX2 instants. When this element is next read MAW operates to light lamp N1. The operator now operates the " search for address" key KSA which resets MAW and operates MEW which lights a lamp N2. The operator now presses the appropriate KC, KM or KN keys to apply potential to coded combinations of leads KT3 ... KT6, thereby causing the code to appear sequentially at instants TX3 ... TX6 on a lead KTW (not shown). Relay MBW is thereby operated. When the reference 0 at TX2, TY8 on the regenerative track is reached MCW operates and the reference marking is deleted. At the next TX1, TY13 element MDW operates to cause a new reference 0 to be written in at TX2, TY13. At the subsequent TX6 element MCW is released. Whilst MCW, MDW are operated the old digit in TX3 ... TX6, TY13 corresponding to the first digit of the address is obliterated and the new digit as indicated on the lead KTW is inserted in the transfer track. At TX6, TY13 MCW is restored. After a further revolution the reference marking releases MBW (provided the code key is released) and one revolution later (to guard against contact bounce) MDW is released. The second key is now. depressed in accordance with the second digit of the address and the digit is written into the TY14 section of the transfer track in a similar manner and the reference marking deleted. The transfer track repeats the two digits in sections TY6, TY7 and TY13, TY14 throughout its length. Relay MFW which is operated at TX2, TY1 and TX2, TY8 is used for comparison of signals on the address track and on the transfer track, being reset whenever two signals from the two tracks are different. When identity occurs MFW remains operated and at TX2 of the next TY1 or TY8 interval MAW is released and a new reference 0 is inserted in the regenerative track and MBW and MDW release as before. Seven sections later MAW is reoperated and MEW, MFW are released. During this period seven sections of the transfer track (and thus effectively the whole track) is cleared. To write in the new library information (in the position determined by the new reference marking) the appropriate key is pressed to produce sequentially coded outputs KTW as before. The keys in question are digit keys KN1 ... KN10 and a blank key KN-, multimetering keys KM1 ... KM6 and timing keys KC15, KC30, KC1, KC3 indicating the intervals in seconds or minutes at which the meter is to be operated. Relay MBW operates and MCW follows when the reference marking is reached. The reference marking is deleted. Relay MDW operates at the next TX6 interval, thereby providing for the deletion of information in the next section (including the provision of a new reference 0 at TX2), the insertion of the new digit in TX3 ... TX6 and the insertion of a 1 in TX1. The latter 1 is used in all cases except the first library digit (which is a metering digit) to indicate that the succeeding digit space contains a digit (i.e. is not left blank). In the case of the first (metering) digit however the TX1 space is used to indicate whether numericals are required to complete the call (1 inserted) or whether the call is a " code only" call (0 inserted). In the latter case the " code only" key is depressed prior to the call changing key to bring up MFW. This prevents the insertion of the 1 in TX1 as previously described, insertion of the keyed digit in TX3 ... TX6 taking place in the usual manner. MCW restores at time TX6 and when the new reference marking is read MDW is released. Insertion of digits in subsequent sections proceeds in a similar manner. If a digit is to be left blank, key KN- is operated to connect potential to lead KT2 so that KTW has an output at TX2 to operate MFW. Relay MDW operates as usual at TX6. This releases MFW which however remains operated sufficiently long to inhibit the insertion of 1 in the succeeding TX1. At the end of each translation block, the operator may type in fresh information in the immediately succeeding block by continuing to depress keys or the start key can be reset to cancel the marking and a search for a different address may be initiated. When all the new library information has been inserted in the regenerative track key KSW is restored and KWW operated. This feeds the information on the regenerative track into the writing head LWN of the library track selected by KYT, the writing-in being completed in one revolution of the drum. Writing intothe address track.-This operation is similar to that of writing in the library track with the exception that TX1 is not to be marked and digits have only to be written in TY6, TY7, TY13, TY14. The key KSW when thrown to the left-hand or " address " position does not energize lead KWL. Accordingly MDW does not operate until period TX1 of TY6, TY7, TY13 or TY14, so that nothing is written in any TX1 element or any of the other TY sections. If the typist makes an error, the " search for address " feature can be us