Patent GB-1301419-A (GB)
IPC: G06K1/12
Filed: 1971-04-19
Abstract: 1301419 Magnetic recording INTERNATIONAL BUSINESS MACHINES CORP 19 April 1971 [14 Feb 1970] 20334/71 Heading G4C and G4M A magnetic recording apparatus includes a memory having two addressable portions, each location in one portion being paired with and having the same address as a location in the other portion, a keyboard for entering data into the memory, a recorder for recording data read from the memory onto a magnetizable medium, and gating means for transferring data from the keyboard into the first memory portion, from the first into the second memory portion, and from the second portion to the recorder, the arrangement being that data is fed to the first portion from the keyboard while data is being supplied to the recorder from the second portion. As described the system may accommodate three programs prepared initially on the keyboard and recorded on a magnetic card, and then tranferred after verification (see below) into the memory via staticizing register 54. The system operates in a number of modes. Entry mode.-Data is entered via the keyboard and register 31, which is connected to a display device, into the first portion D1 of the memory 34. The control of entry is by means of one of the programs selected by the keyboard) stored in the program portion of memory 34. When the entry is complete the data is transferred to portion D2 and further data may be entered in D1. The data from D2  is then written on to a magnetic card by the recorder 56. The program selected may force spaces into the portion D1 during entry, or shift a number of entered characters to the right and fill the vacant spaces with zeros. Verification mode.-A track of a magnetic card is read into D1. The operator then rekeys the data, successive characters entering the register 31 being compared with the corresponding locations in D1. In the event of a mismatch the relevant character is overwritten from the keyboard. The data in D1 may also be compared with the contents of D2 if required. Following verification the data is transferred to D2 for re-recording if necessary, i.e. if errors have been corrected. Prior to the re-recording fresh data may be read into D1 from the card for verification in order that the operator does not have to wait for the rerecording to be completed. Comparisons may be made of the data at addresses selected by the keyboard in D1 and D2. Errors may again be overwritten.  Read mode.-Card data are read into D1 from where they are transferred character by character to register 31 for display. Overwriting of selected characters is achieved by temporarily changing into the entry mode. Search mode.-The search pattern is loaded into D1 from the keyboard, spaces being loaded into positions not germane to the search. The pattern is then shifted into D2 and the selected cards read into D1 via register 54, a comparision of each entered character and the appropriate character in D2 being made. In the event of a positive non-compare (i.e. not involving a space in D2) the search of the current card is terminated. When a card has been matched its contents may be displayed by means of display 33. Further details.-Transfers of data between D1 and D2 are made in parallel. All addressing operations are under programe control except where the program specifies manual (i.e. keyboard) addressing.