Patent GB-1369383-A (GB)
Title: Data storage apparatus
IPC: G06F17/22
Filed: 1972-11-17
Abstract: 1369383 Selective signalling INTERNATIONAL BUSINESS MACHINES CORP 17 Nov 1972 [30 Dec 1971 (2)] 50052/72 Headings G4H and G4A Data storage apparatus comprises a closedloop shift register operable to store a series of codes, the series including two sections of character-representing codes divided from one another by a separator code, the series also having controlling codes which define reading/ writing zones in each section, decoding means to detect the controlling and separator codes passing between input and output stages of the shift register, data entry and receiving means, and gating means operable, in response to the decoding means, to gate character and controlling codes from the data entry and receiving means into the series of codes and from the series of codes into the data entry and receiving means. The shift register is n bits wide. Its output feeds the decoding means and can be fed via a first buffer register, a normal register, an insert register and a second buffer register back to the input of the shift register, though usually the insert register is by-passed. Both the normal and the insert registers can be by-passed. A data buss connected to a printer and keyboard, and to a reader-recorder, can be fed from the first buffer register and can feed the second buffer register. An operation code can be provided in one section to define it as "the addressed section" and a hold code provided in the other section. A record code can be provided in the addressed section, the region between it and the separator code being the zone in use, e.g. for revision. A section button on the keyboard is used to specify the addressed section and if this is inconsistent with the specification provided by the operation and hold codes the latter are automatically interchanged by applying a hold code from the data buss while the operation code is in the normal register and vice versa, the codes in the normal register being discarded. Similarly, character codes can be input from the buss while the separator code is in the normal register (this code being discarded), new separator and hold codes being entered after the characters. The operation code defines the point at which revision can be made. A page end code can be entered to define a read-out zone, which extends to it from the record code, the page end code being inserted after the last character code in the revision zone, the operation code being automatically repositioned between the page end code and the separator code, as follows. When the operation code is in the normal register, subsequent codes by-pass the normal and insert register until the separator code enters the first buffer register when the separator code is gated to the normal register (the operation code in the normal register having passed to the insert register). A page end code is entered from the data buss (into the second buffer register). Signal flow now goes through all the registers until the hold code is in the second buffer register, when normal signal flow (by-passing the insert register) is resumed. During the output operation, the record code is held in the normal register while the codes following it, up to and including the page end code are output to the data buss, the record code then being reinserted in the signal flow in the shift register. A check-read operation can be performed. Input, output and revision operations, involving many changes, can be performed in each shift register revolution.