Magnetic tape scan with field selection

Claim 1

IN AN INTERNALLY PROGRAMMED COMPUTER HAVING A MAGNETIC TAPE STORAGE UNIT IN WHICH WORDS ARE STORED ERIALLY, APPARATUS CONTROLLED BY THE COMPUTER FOR AUTOMATICALLY POSITIONING THE TAPE FOR LOCATING A WORD ACCORDING TO SELECTED DIGITS IN THE WORD, SAID APPARATUS COMPRISING ADDRESSABLE MEMORY MEANS FOR STORING OPERAND AND INSTRUCTION WORDS, A REGISTER FOR STORING INSTRUCTION WORDS, REGISTER MEANS FOR STORING AN OPERAND WORD, MEANS RESPONSIVE TO A FIRST GROUP OF PARTICULAR DIGITS STORED IN THE INSTRUCTION REGISTER FOR INITIATING READOUT FROM THE MAGNETIC TAPE, MEANS RESPONSIVE TO A SECOND GROUP OF PARTICULAR DIGITS STORED IN THE INSTRUCTION REGISTER FOR TRANSFERRING A SELECTED OPERAND WORD FROM THE MEMORY MEANS TO THE OERAND WORD REGISTER MEANS, THE TRANSFERRING MEANS INCLUDING MEANS FOR SELECTIVELY MODIFYING ANY DIGIT TRANSFERRED TO THE OPERAND REGISTER TO A SPECIAL DIGIT VALVE DIFFERENT FROM ANY NORMAL DIGIT IN AN OPERAND WORD, FIRST AND SECOND COUNTERS, MEANS RESPONSIVE TO A PAIR OF DIGITS IN THE INSTRUCTION WORD STORAGE REGISTER TO A PAIR OF DIGITS COUNTERS TO PRESELECTED COUNT CONDITIONS, MEANS FOR COUNTING THE FIRST COUNTER IN SYNCHRONISM WITH THE TRANSFER OF DIGITS OF THE OPERAND WORD TO THE OPERAND REGISTER, MEANS RESPONSIVE TO THE FIRST COUNTER IN ITS ZERO STATE FOR INHIBITING SAID MODIFYING MEANS, WHEREBY THE DIGITS ARE MODIFIED DURING TRANSFER UNTIL THE FIRST COUNTER IS COUNTED TO ZERO, MEANS FOR INITIATING COUNTING OF THE SECOND COUNTER IN SYNCHRONISM WITH THE TRANSFER OF DIGITS TO THE OPERAND REGISTER, MEANS RESPONSIVE TO THE FIRST AND SECOND COUNTERS IN THEIR ZERO STATES FOR REACTIVATING SAID MODIFYING MEANS, WHEREBY ONLY THOSE DIGITS OF THE OPERAND TRANSFERRED DURING THE COUNTING OF THE SECOND COUNTER ARE TRANSFERRED TO THE OPERAND REGISTER MEANS WITHOUT MODIFICATION, MEANS FOR DRIVING THE TAPE, MEANS FOR READING OUT SOTRED DIGITS SERIALLY FROM THE TAPE, MEANS FOR STARTING THE TAPE DRIVE AFTER THE OPERAND WORD HAS BEEN TRANSFERRED FROM MEMORY TO THE PERAND REGISTER AND READING OUT WORDS FROM TAPE SERIALLY DIGIT BY DIGIT, MEANS FOR TRANSFERRING ANOTHER INSTRUCTION FROM THE MEMORY MEANS TO THE INSTRUCTION REGISTER WHEN TRANSFER OF THE SELECTED OPERAND WORD TO SAID OPERAND WORD REGISTER MEANS IS COMPLETE, WHEREBY THE COMPUTER CAN PERFORM OTHER INSTRUCTIONS WHILE THE TAPE IS BEING READ, MEANS FOR SHIFTING THE OPERAND REGISTER IN SYNCHRONISM WITH THE TAPE READOUT, MEANS FOR COMPARING EACH DIGIT OF A WORD READ OUT OF TAPE WITH EACH DIGIT SHIFTED OUT OF THE OPERAND REGISTER TO SENSE FOR EQUALITY, SAID COMPARING MEANS INCLUDING MEANS FOR INTERPRETING EACH OF SAID MODIFIED DIGITS OF SPECIAL VALVE AS EQUAL TO ANY DIGIT FROM THE TAPE, AND MEANS RESPONSIVE TO THE COMPARING MEANS FOR INTERRUPTING THE TAPE DRIVE AT THE END OF A WORD READ OUT OF TAPE WHEN EQUALITY IS SENSED BY THE COMPARING MEANS BETWEEN ALL OF THE DIGITS OF THE TAPE WORD AND THE WORD SHIFTED OUT OF THE OPERAND REGISTER.