Patent GB-1012117-A (GB)
Title: Improvements in or relating to data storage systems
IPC: G06F17/30
Filed: 1964-09-30
Abstract: 1,012,117. Electric digital data-storage. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 30, 1964 [Oct. 1, 1963], No. 39734/64. Heading G4C. In a data storage system, an address is associated with a random number by sequentially associating the digits of the random number with addressable positions storing intermediate numbers and using the intermediate number stored at the addressable position associated with one digit to determine the address of the position to be associated with the next digit, there being means to insert a number corresponding to an address at the addressable [position associated with the last digit of the random number. In the particular embodiment, information is transferred between a computer memory (e.g. cores) and a large capacity so-called " random access " memory (e.g. magnetic cores, discs, drums or tape strips), addresses in the latter being chosen with the aid of a directory memory 111 (e.g. cores) which stores such addresses. Transfer to " random access " memory.-An. instruction word to achieve this, read from the computer memory, specifies the operation, the address in the computer memory of the first word of the record to be transferred, the type of record (e.g. whether it belongs to a personnel file or an inventory file-single character used), and an identifier (e.g. a personnel or part number-plurality of characters used). The type character and identifier characters are read into registers 102 and 104 respectively (Fig. 3). Also shown in Fig. 3 are a 3-character random address register 115, the two highest order character positions of which constitute an indirect address register 106, and a directory memory address register 110 used for addressing the directory memory 111. The type character at 102 specifies (initially) the higher order digit (character) in the indirect address register 106, the other being (at this time) zero. The contents of register 106 are stored in the two highest order positions in register 110 and a digit from the identifier register 104 selected by the type character is placed in the lowest order position in register 110. Register 110 is used to address the directory memory 111 and the read-out word is stored in random address register 115. If the word is of blank characters, the first available address stored in a part of the directory memory called the directory address reservoir is stored in the memory location from which the blanks came and in the random address register 115, and the control 120 which selected the said first available address is decremented by one. The new contents of the indirect address register 106 (which as stated is a part of register 115), together with the next digit (character) from the identifier register 104 are read into register 110 and the above process repeated. This continues until the last digit of the identifier register 104 (i.e. excluding those occurring before the first used) has been placed in register 110. The contents of this register are used to address the directory memory 111, and if the word read-out is of blanks, the blanks are replaced as before except that the address comes from a random memory address reservoir 124 the control 126 of which is then decremented by one. The address now in the random address register 115 is used for addressing the " random access " memory and the information is transferred to this memory. The addressing is by multi-word sectors and if the record will not fit into one sector, the address of another is obtained from the directory memory as above (except that the new address is not stored in the directory memory) and the address of the second sector is stored in a transfer address portion of the first sector. The last sector used for a given record contains an " end-bit " (E/B) mark in its transfer address portion and also an "end-record" (E/R) mark. Any unfilled character positions in the last sector are filled with blank characters (this is not true in the computer memory). Transfer from " random access " memory.- The obtaining of the " random access " memory address from the directory memory is done as before except that no blanks arise to be replaced with addresses from reservoir. It is also mentioned that erasing may be done. Fig. 20 (not shown) shows a circuit for producing core memory read and write signals.