Decoding device

专利名称：Decoding device发明人：STEVENS LOUIS D.申请号：US67700457申请日：19570808公开号：US3082406A公开日：19630319

摘要：1,338. Electric digital data storage apparatus. INTERNATIONAL BUSINESSMACHINES CORPORATION. Aug. 6, 1958 [Aug. 8, 1957; Aug. 23, 1957], No. 25150/58. Class106 (1). In an arrangement for converting an address from one coded representation toanother addresses in the first form are stored at discrete locations of a data storeidentified by addresses, means are provided for scanning the locations in sequence anddelivering information read from each in turn to a comparing device also receiving inputsignals in the first form, and output means actuated by agreement between the sensedaddress and the input signals for providing an output in the second form. The locationsof the store are numbered in sequence and this number is the second form abovereferred to, or the \" internal address.\" The first form of the address is a catalogue orserial number which may bear only an arbitary correspondence with the internal

addresses. This form is termed the \" external address \" and the purpose of the inventionis to convert the external address to the internal address so that read-out from the storemay be under the control of an external address. In the form of Fig. 1 the store consistsof a number of magnetic discs 11 mounted on rotatable shaft 12. Reading or writingheads 14 co-operate with either side of each disc, the heads being carried on arms 15secured to shaft 16, the radial position of which is controlled by mechanism 17 to position

the heads on the selected tracks of the discs 11. The tracks are concentrically arrangedand the locations are numbered in sequence, any desired location being selected by theinternal address selector 20 which stores the number of the desired address and at anappropriate time, by transference of switch contacts 21a, controls the positioningmechanism 17 to select the track indicated in the address. The address may also indicatethe disc containing the desired data or when the data is read-out in parallel form from anumber of discs it may indicate a storage position on each of a number of tracks. Thisindication is passed over line 22 to control further selection circuitry. A clock track disc11a produces clock pulses which are amplified at 24 to produce A and B pulses, the latterlagging. Reference marks on disc 11a produce \" start scan \" signals on line 27 to indicatethe start of all storage tracks. The external addresses are recorded in parallel form inone or more tracks of each disc. These tracks are first scanned and the signals derivedare amplified at 38 and compared in comparator 39 with the contents of the externaladdress register 30. The number of storage positions scanned before the comparatorindicates agreement is the internal address, since this is the number of the desiredlocation in the series along the track. Operation.-The external address is entered on line31 into store 30 and a \" scan control \" signal is then applied from terminal 29 to theexternal address scan control 28. This signal transfers switch contacts 21a to contact thepositioning mechanism 17 to the external address scan control, which positions the heads14 on the external address tracks of the discs. If more than one track is used for theexternal addresses, the scan control 28 steps the heads to the next track after eachrevolution. The next start scan signal on line 27 resets counter 33 and opens gate 34 toallow the \" A \" clock pulses to pass to it. There is one pulse for each storage location andthe value in the counter therefore corresponds to the internal address number. Thiscount is applied via a converter 35 to the internal address selector which, when connectedto the mechanism 17 positions the heads on the corresponding tracks. When the externaladdress sensed agrees with that in the store 30 the comparator 39 closes gate 34 andtransfers switch 21. The counter therefore receives no more pulses and the value therein,

which is the internal address corresponding to the external address in the store 30,becomes effective to position the heads 14 on the corresponding address of the discstore. Entry of new external addresses.-A blank location in the external address track isdetected by detector 41 which opens gate 43 to transfer the count in counter 33 to theregister 45. The gate is closed by the next following \" B \" pulse to prevent more than onecount being transferred. The signal from detector 41 also primes a trigger 46 which is setby the next start scan signal on line 27 to allow \" A \" pulses to pass through gate 47 tobe subtracted from the value in register 45. When the value becomes zero, the blankexternal address locations are under the reading heads. The \" B \" pulses on line 26 areaccordingly passed to the write matrix 52 to write into the blank location the addresspresent in the store 30. The relay contacts 37a-37n are transferred for the writingprocess. Second embodiment.-In a modification (Fig. 2, not shown) both the external andthe internal addresses are stored, being in corresponding positions on different groupsof discs so that corresponding external and internal address are read simultaneously. Asbefore the external addresses are read and compared with an external address enteredin a store. The internal address sensed when agreement occurs is entered into a registerand used to control the positioning mechanism for read-out of the desired data. Newexternal addresses are entered serially, the next blank location being indicated by aninternal address register. A counter is operated by clock pulses as before and its count iscompared with the internal address register. An output therefore indicates that theblank position has been reached and the new external address is written into theappropriate tracks, the value in the internal address register is written into the internaladdress tracks and the value in this register is increased by one to indicate the address ofthe next blank internal address location. Specification 823,748 is referred to.

申请人：INTERNATIONAL BUSINESS MACHINES CORPORATION

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