Patent GB-1370400-A (GB)
Title: Recording apparatus
IPC: G06K1/12
Filed: 1972-12-13
Abstract: 1370400 Selective signalling INTERNATIONAL BUSINESS MACHINES CORP 13 Dec 1972 [30 Dec 1971] 57477/72 Heading G4H  Apparatus for recording information, comprises entry means (e.g. a typewriter keyboard) for entering the information, the information being recorded in block-organized storage means (e.g. tape, disc or cards) under the control of control means which assign the information to the storage blocks by reference to a record ("machine log") indicating which storage blocks have previously been assigned to, the entry means being operable, under the control of the control means, to revise the stored information by deleting portions thereof and revising the assignment of the remaining information between the storage blocks, the control means being operable, in response to a revision which results in one or more previously assigned storage blocks being made available for re-assignment, to cause the ("machine log") record to be updated. A recirculating shift register receives information entered by the keyboard, divided into "pages" for one or more "jobs". The shift register can hold two or more pages. A page in the register can be recorded in a block of the storage means, the block being selected automatically using the machine log which keeps account of the sequential ordering- of each page of each job and where each page is located in the storage means. This recording can be ordered by the operator and can take place while the operator is entering another page. A record error in a block causes the next available block to be used, the erroneous block being ignored thereafter. Revision involving insertion, deletion, amendment and changing of page boundaries which are delineated by special codes, can be preformed under keyboard control, the pages being brought from the storage means into the shift register for this purpose, an operating flag also being held in the shift register. When one page has been brought into the shift register, the next will be automatically brought in if at least 3,000 character positions are left free (to avoid incomplete bringing of a page) and so on. Revised pages can be recorded back in the storage means and deleted from the 'shift register, unchanged pages simply being deleted from the shift register, since they are still in the storage means. If the operator makes so many inserts that space in the shift register is running out, the last page in the register is eliminated from the register (with updating of the machine log) unless it has been revised or the operating flag is within it in which case further insertions beyond a certain limit cause the operator to be notified to define a new page end and transfer some of the data into the storage means. A page counter counts the page delineation codes in the shift register as it recirculates; the count being used at the end of a circulation to load a page register which is subsequently compared with the page counter to indicate the last page in the loop. A 6-bit page revision shift register indicates which page in the shift register the operating flag is in and which pages in it have been revised, in that when the operating flag is detected during circulation a bit of the page revision shift register selected by the page counter is set.