Patent GB-793339-A (GB)
Title: Improvements in or relating to card-to-tape converter
IPC: G06F11/00
Filed: 1956-06-13
Abstract: 793,339. Statistical apparatus. SPERRY RAND CORPORATION. June 13, 1956 [June 13, 1955], No. 18331/56. Class 106 (1). Card to tape conversion.-In apparatus for reading data from record cards and converting it to representations on magnetic tape photoelectric means 90, Fig. 4, are provided for initiating an impulse as the card passes under the sensing brushes 87, this pulse being recorded by head 83 on a magnetic disc 82, rotating in synchronism with the card-feeding rollers, and then read by head 84 and applied both to the sensing brushes as they sense the first index position and to the write head 83 thereby recording a second pulse which is read later by read head 84 to energize the brushes as they sense the second index position and to record a third pulse and so on. The successive pulses are also transmitted to a counter 60 which opens read-in gates of each row in turn of a memory device 50 so that the data sensed by the brushes is stored. The data is read out of the memory device, recorded on magnetic tape and also compared with the data on the card sensed at a second sensing station 88. Where there is disagreement the card is rejected to an " error " pocket. Card sensing.-The cards are fed from a hopper, passed by continuously rotating rollers through the two sensing stations and then carried by grippers on a stacking roller either to a stacking bin or to the error pocket according as to whether or not an error has been detected. One of the feed rollers has fixed to its shaft the magnetic disc 82 with which cooperate three heads 83, 84, 85 for writing, reading and erasing. The brushes in each sensing station are similarly arranged in a line across the card. Voltage is applied to each line of brushes so as to sense the index positions of all columns as the card passes thereunder. The photo-electric device 90 detects the leading edge of the card as it passes under the brushes 87 and sends a pulse through an amplifier to a gate G100 which is open only while the row counter 60 is on row " one " and which passes the pulse to a delay device DF 105. The output pulse from the delay device energizes the sensing brushes 87, energizes the writing head 83 and through a further delay device DF 106 steps the row counter 60 at the completion of the sensing of each row. After the pulse has circulated through the writing head, the reading head, gate G101 and delay device DF 105 fourteen times an output from the counter closes the gate G101, to stop the circulation. The pulses are relayed from the delay device DF 105 to the sensing brushes through a gate G102 and energize them for the whole of the time a card perforation is passing under them. The row count " one " causes a signal on line 102 to disable gate G101 and open gate G100 but on stepping to count " two " gate G101 is opened and gate G100 is closed. The leading edge pulse from photo-cell 90 therefore enters the circulation path through gate G100 which then closes to prevent the entry of unwanted pulses. The circulation is effected through gate G101 this continuing until all card rows are sensed and then being stopped by the closing of gate G101. The counter 60 consists of four binary counters having a count of 16, two of which are deleted to reduce the count to 14. The first row is sensed while the count is at one and the data is transferred to vertical core windings of the magnetic memory matrix 50, the horizontal core windings being energized in turn by the counter. The subsequent rows are read in the same manner and the data transferred to subsequent rows of the core memory. Tape feeding and recording.-The data is read out of memory (as described below) on to tape which is set moving before the end of the sensing operation. The information is recorded on the tape in blockettes of 120 characters, the blockettes being separated by gaps of about one inch and each group of six blockettes, comprising a single block, is separated from the next group by a gap of 2.4 inches. Residual signals on the tape are removed during this recording by application of an erase current to recording head 40 as described in Specification 665,179. The tape is set moving and when it has attained full speed the erasing current is gradually applied, the recording is made and the erase current gradually removed. This gradual application and removal avoids recording transients which would be read as spurious pulses. Each digit is represented by a code combination in seven channels and a succession of " sprocket pulses is recorded in an eighth channel for timing purposes. The tape is moved forwardly to give the spacings between the blocks and blocketts during recording; it is moved backwards to make " odd-even " checks; to make checks to determine if the capacities of the blockettes are greater or less than 120 characters, and moved forwardly again to check information recorded on the tape against information read out of the memory during the second reading of the card. The odd-even check which is made three times determines if the number of " ones " in any one character position is odd or even, an even count indicating an error. If an error is detected in either the odd-even check or the greater or less than 120 check the card and tape units are stopped. The number of cards converted is counted and " mispunch " circuits (described below) reject any cards with punched combinations which have more than two holes and cannot be interpreted. After all the information from the card has been sensed and transferred to the memory the tape is set moving and the information transferred to it from the memory. The tape then stops, the head 40 is switched from record to read and the tape drive clutch is reversed. During the next interval the card is sensed at the second brushes 88 the data being read into memory as before and while this is in progress the tape begins to move in the reverse direction past the reading head 40. The " odd-even " and " greater or less than 120 " checks are then made and the tape stopped. The feed controls are then switched again from reverse to forward drive and the tape begins to move in the forward direction. The converter is then switched from " check " to " read " and the information read out from the memory is compared with that recorded on the tape. The tape is then stopped and the converter switched from " read " to " record " ready for the beginning of the next cycle. Memory read-out.-The data is read out of memory column by column, each column representing one digit in a blockette. There are only eighty columns in the memory so that forty " nil " or " fill " digits are automatically inserted to make up to 120-the contents of each blockette. The columns of the memory are read out in any desired order as determined by jack connections on a plug-board interposed between the memory and a column counter. If the counter is plugged to read out the columns consecutively it signals the memory to read out column 1 when it is on count one. The output from the column counter is gated by a pulse cycling unit which determines the exact time the column of memory is read out. The information in each column of memory is transferred in turn to an encoder 75 which translates the information into the tape sevenbit code. The output from the encoder is passed through seven gates and amplifiers to the seven coils of the recording head 40 so as to record the data on the tape. The pulse cycling unit recycles eighty times so that all columns of memory are read out in turn. Odd-even check.-As each digit is recorded it is also passed to the odd-even checker 143 which counts the " ones " in the digit to be recorded. The code represents the digit part of the card (1-9) in four channels and the zone parts (X, Y, O) in two channels. The seventh channel is used to insert a further digit where necessary to make the total number of ones in the digit odd. The odd-even check merely ensures that a recorded digit contains an odd number of ones, it does not check its accuracy. If the checker detects an even number of digits it passes the card to the error bin, records an error signal on the tape and lights a lamp in the control panel. After the recording on the tape the tape feed mechanism is stopped and prepared for reverse drive. Second sensing.-In its progress towards the second sensing station the leading edge of the card comes under the leading edge detector 95. This causes a pulse at gate G100 which is passed to write head 83 and recirculated through gate G101 as before to energize the brushes 88 at each card index time. To discover whether the cells of the memory unit are operating correctly the rows of memory are energized in a different order during the second reading. For this purpose the counter 68 is connected to the rows of memory through switch contacts which when reversed alter the sequence of energization of the rows. The data sensed on the card is transferred to the rows of memory as before and during this process the tape starts moving in the reverse direction for the second oddeven check and a greater or less than 120 digits check. After this reverse movement the tape again moves in the forward direction past the read head 40. The data is read out of memory as previously described but instead of being passed to the encoder 75 it is transmitted to the comparator 45, the information on the tape being read into a decoder 99 to convert it back to the card code. The output from the decoder is compared with the output from the memory and each time a comparison is made an odd-even check takes place. When 120 digits have been compared and found correct the card is taken by the gripper drum and stacked. If a discrepancy is found the machine stops and if desired the tape can be re-positioned and the card passed through again. The comparator consists of twenty-four gates twelve for the twelve rows of information in the memory and twelve for those in the decoder. The gate