Patent GB-776018-A (GB)
Title: System for recording punched card data on magnetic tape
Filed: 1954-12-24
Abstract: 776,018. Statistical-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 24, 1954 [Dec. 31, 1953], No. 37386/54. Class 106 (1). [Also in Group XL (b)] An electronic data processing system comprises means for sensing data in one code system on a punched record card, means for translating the sensed data into a second code system, and means for transferring the translated data to a magnetic record tape. A sensing unit 14, Fig. 1, simultaneously senses the twelve rows of a moving punched card in column by column order and provides corresponding successive varying combinations of discrete electrical impulses. The impulses are individually amplified and shaped in a unit 16 and fed to a code translating matrix 18 for conversion into discrete pulses which pass through a gate unit 26 and selectively energize the magnetic tape writing heads in a unit 20 in accordance with the excess three code. In a card position sensing unit 22 the leading edge of the card produces a series of discrete pulses corresponding in time to the particular column being sensed by the unit 14. These pulses are shaped in a unit 24 and are applied to the gate unit 26 which ensures that the output from the matrix is passed to the writing heads in correct column by column order. The cards are fed lengthwise along a track 34, Fig. 9, past a group of twelve data-sensing photo-cells 40a- 40l and over a timing track 42 comprising eighty-two separate light-transmitting slots below which are located focusing prisms 46, 50, 54, 56, each associated with photo-multipliers 48, 52, 58, 60. A light source 44, Fig. 9a, is provided for the cells 40a-40l and prisms 46, 50, 54, 56. Before the cells 40a-40l is a photo-cell unit 38 which when triggered by an advancing card provides a pulse used for starting and stopping the magnetic tape. As the card advances its leading edge successively and sequentially covers the slots in the timing track 42 causing a progressive diminution of the light falling on the photo-multipliers 48, 52, 58, 60, across a resistor load of which a corresponding stepped voltage wave is obtained. This wave is differentiated to provide a series of discrete pulses which after sharpening and shaping are, as stated above, applied to the gate unit 26, Fig. 1, to gate the various writing circuits comprising trigger circuits which on operation provide a change in the direction of magnetization of the tape. For a particular card the first timing impulse causes the writing circuits to make a field mark on the tape. The subsequent timing pulses are simultaneously applied to one of the inputs of seven gate units. The simultaneous application of a pulse to the other input of a gate unit representative of translated data from the matrix results in the unblocking of said gate and the sending of an impulse to the corresponding tape writing head. The last timing pulse obtained from the track 42 serves to provide a field mark of predetermined coding. The tape is also marked with a record mark indicative of the end of the data for a given card. For checking purposes the matrix is so arranged that an odd number of bits is always marked on the seven tracks of the tape, a bit being provided on the seventh track where necessary. Specification 733,807, [Group XXXV], is referred to.