Patent GB-777910-A (GB)
Title: Tape to card and card to tape converter
IPC: G11C11/23
Filed: 1955-11-24
Abstract: 777,910. Statistical apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 24, 1955 [Nov. 26, 1954], No. 33723/55. Class 106 (1). A machine for transcribing data from punched card records to magnetic tape and vice-versa, comprises a storage device having data input circuits adapted to selectively receive data from punched card reading means or from a tape reading device, switching circuits connected between the input circuits and the tape and card reading means, means for conditioning the switching circuits to enter into the storage device from either tape or card reading means, a card punch, a record tape reproducing device, means for operating the punch under control of data stored in the storage device by said tape reading device and means for operating said tape reproducing device under control of data stored in the storage device by the card reading means. The punch has means to punch the data and a check count thereof into each card and means for reading the punched data, means for generating a check count of the data so read and means for comparing the generated check count with that punched in the card. The accuracy of punching is thereby checked. When data is being read from cards each card is read twice, the first reading being used to generate a check count which is transmitted to the storage device with the second reading of the data. The data is carried on the tape in one coded notation while on the card it is represented by another, means being provided between the card reader and the storage device and between the storage device and the card punch, for translating data from one code to the other. General.-The machine comprises a reproducing punch which operates as a punched card reader when data is being transcribed from card to tape and a card punching machine when data is transcribed from tape to cards. The punch is coupled through an electronic circuit to a magnetic tape unit. This machine is adapted to make data on punched cards available to a computer designed for exclusive use of magnetic tape. Similarly it enables output data from such a computer to be transcribed to cards. The reproducing punch reads and punches cards having 80 columns using a 12 unit code so that input and output from the punch is on 80 parallel lines and takes the form of signals at 12 sequential time intervals. The signals to and from the tape are on four parallel lines each set of simultaneous signals constituting a character, characters therefore being read out in serial fashion. Because of the speed of operation of the computer with which the tape is to be used it is necessary to run the tape intermittently and to record blocks of data from cards, these blocks being separated by blank inter-record spaces in which the tape is started and stopped. The same procedure is followed in tape to card conversion. The tape is started, a complete record block is sensed and stored in a memory and the tape stops in the inter-record space. The punch then begins to punch cards, reading up to 80 characters from memory in each punch cycle until the whole record block is transferred to cards. The tape then starts again and the process is repeated. Information on tape.-The arrangement of information on the tape is shown in Fig. 2A. Each word consists of 18 character spaces including an " end-of-word " code character. This is shown in Fig. 2 illustrating the usual storage tape organisation, the information being recorded in a solid block. In Fig. 2A the data is divided into sub-blocks of 100 words separated by a tape starting and stopping space of one inch. An end of block character (13) marks the end of each recorded block and the end of word character (12) marks the beginning and end of each word within the block. An end of block word begins and ends each block. Sub-blocks of 100 words contain 1800 characters. These are stored in a fourdrawer memory device between reading from tape or cards and being recorded on cards or tapes. The tape code used, shown in Fig. 3, is a modified binary code, a signal in any position indicating the absence of a mark in that position. This provides that there will always be a signal in at least one track in every position irrespective of the number represented. Zero is represented by a signal in all four tracks. Also the "4 " and 8" tracks have been reversed so that there is always a signal in one or both centre tracks. This provision is used to minimise the effect of tape skew while passing the read-write heads, the character gate timing being derived by sensing only the centre two tracks. Machine arrangements.-Tape to card.-Fig. 4 shows the flow of information in the converter. In the case of tape to card conversion, the operation is as follows. The tape unit 10 feeds tape through the read-write heads, the first character sensed producing an output signal on one or more of lines 12. These signals set one or more of four triggers in a first tape register 14. Setting of the corresponding triggers in register 14 causes a signal on a line 16 to initiate a character gate 18 which is a time delay unit set to about seven microseconds (half the time interval between characters). The end of this time delay is used to reset the register 14, which has now had time to receive the most retarded bit of the character being read. The register is then ready to receive the next character. Resetting of register 14 gives signals on lines 20 to set corresponding triggers in a second tape register 22. The end of the character gate time delay also initiates one bit-storage cycle in the memory units, which extends for eight microseconds. The memory unit consists of sixteen cathode ray tubes of eight of which are shown in Fig. 5. Four tubes are provided for each of the tracks of the tape. Initially the deflection controls of all sixteen memory tubes are conditioned to deflect the beams to the left spot of the upper row of all the tubes the tubes 1 being unblanked to write a dot or dash. Tubes 2, 3 and 4 remain blanked at this time. The four triggers of the second tape register 22 are connected through tape-card switches 24 to the dot-dash control circuits 26 of the four corresponding memory drawers, 28(1), 28(2), 28(4), 28(8). The setting of any trigger causes the dot-dash controls to store a dash in the corresponding memory tube. In this manner a dash is stored in the upper left spot of the memory deck corresponding to the tape tracks in which signals were sensed for the first character. Dots are stored where no signals are sensed. Completion of the eight microsecond bit storage cycle steps the horizontal deflection circuits 30 so that the next character is recorded in the second spot in the top row of tubes 1 of all four memory drawers and the action is repeated until 18 characters have been stored. The deflection circuits 30 then return the cathode ray beams to the extreme left position and the second tube is unblanked so that a subsequent 18 characters are stored in the top lines of these tubes. The process is repeated for the third and fourth tubes of each drawer, a further 18 characters being stored in each case. After 72 characters have been stored, the vertical deflection circuits 32 step the cathode ray beams down one line and the storage sequence is repeated. The tape continues running until a complete sub-block of 100 characters has been stored at which time a character counter stops the tape in a subblock space. The last sub-block may have less than 100 words in which event the end of block character (a "13 ") will stop the tape. After a sub-block of characters has been stored in memory as described above punching of the first row of card holes will begin in the reproducing punch. The punch sets up a punch coder 34 to provide signal levels on lines 36 representing the four bit equivalent of the digit value of the row of holes being punched. A comparing circuit 38 compares the coded value represented by the signals on lines 36 with the output from memory. The memory tubes are scanned at high speed (8 microseconds per character) in in the same sequence used for reading from tape so that the four memory output lines carry signals wich successively represent the characters read into memory from the tape. Characters 1 to 72 are scanned for the first row of the first card, the cards being passed through the punch in row-by-row order, 80 columns at a time. When a match is detected in the comparing circuits, between the signals on the memory output lines and the signals on lines 36 from the punch coder a signal is sent on line 40 to a scanning matrix 42. This matrix is a switching circuit with 72 output lines conditioned by the horizontal scanning controls, so that a signal on line 40 causes a signal on one of the 72 output lines corresponding to the column of memory being sampled. Signals on the output lines fire corresponding thyratrons 44 which are connected to the punch magnets in the reproducer 46. Holes are thereby punched in the first row in columns corresponding to the columns of memory containing signals. After the first row of the card is punched, the action is repeated for the following eleven rows, the first line of memory (characters 1-72) being scanned again for each card row and holes being punched where coincidence is registered between the punch coder and the output from memory. When the card is completely punched, the next card moves into punching position and the scanning beams in the memory tubes move vertically one step to read out the next 72 characters, i.e. the second line. This is continued until all the memory is read out and transferred to 25 cards, after which the tape starts to move again and a new sub-block of words is read into memory. Verifying.-The seventeenth character of each word is an indicated bit count (see Fig. 2). This is derived by adding up all the bits for the 16 remaining characters of the word reducing the sum to modulo 4 so that the resul