Patent GB-1430483-A (GB)
Title: Data processing apparatus
IPC: G06F3/02
Filed: 1973-05-18
Abstract: 1430483 Selective signalling ARTHUR D LITTLE Inc 18 May 1973 [18 May 1972 (5)] 23874/73 Heading G4H Data processing apparatus comprises a printer and a memory with means for inserting an extra coded signal between signals read from the memory prior to re-storing them, a translator and a signal recording-and-playback means being connected to the memory for selective signal transfer in either direction. A typewriter with a unitary print head is connected to an auxiliary unit in which data and function characters entered on the typewriter keyboard are stored, each in parallel-by-bit form, in a recirculating loop consisting of a 200-character shift register and two one-character registers in series. The registers can be clocked in either of two sequences and shifted by 1, 199, 200 or 201 character positions for an effective one position left or right displacement or clearing (the latter in conjunction with a reset signal applied to the second one-character register). The signals in the loop can be transferred, on typing of a carriage return, with parallel-to-serial conversion, on to a magnetic tape (in cassette) as a block (representing one printed line). The block is accompanied by an address on the tape and can be subsequently read off, converted back to parallel-by-bit, and reinserted into the recirculating storage loop from which it can control the typewriter. In a draft mode, information can be entered on the typewriter keyboard to give an initial recording of a document and make editing changes, e.g. back-space the typewriter and storage loop and correct by overtyping, delete characters in the loop and close up the gap thus created, or (by switching to an insert mode from the draft mode) insert extra characters between already-entered characters. In a final mode, the (edited) information can be typed out with automatic right-hand margin control and, if desired, selective skipping. The keyboard can be used to type further information during this. The manual controls on the auxiliary unit are: (a) draft mode, final mode and insert mode buttons, (b) character, word, line and automatic (i.e. continuous) buttons for controlling the amount printed from the storage loop, (c) a system on button, (d) a stop printing button, (e) character, word and line buttons to control deletion during draft mode and skipping during final mode, (f) step right and left buttons for moving the information in storage and stepping the print head correspondingly, (g) tape forward and back controls with slow and fast speeds. Audio and visual indicators are provided, e.g. a light in the insert button, and lights to indicate whether buttons (e) will cause deletion or skipping. During slow forward movement of the tape, the addresses are read from the tape and loaded into a counter from which they are displayed on the auxiliary unit. During fast forward or slow or fast reverse movement of the tape, the counter is incremented or decremented by pulses produced from the envelope of the addresses on the tape. The counter contents can also be printed out by the typewriter at the beginning of each line (in the draft mode) if a notate button indicates this is required. Automatic right-hand margin control.-When the print-head reaches the beginning of a return zone during printing out of the storage loop contents, the loop is searched for a space, carriage return or hyphen code which would be reached within the return zone. If one is found, printing continues up to that point then a new line is started. If one is not found, printing stops, and an audible or visual indication is given to the operator who must release one character at a time for printing until a suitable opportunity for a hyphen occurs when he must strike the hyphen key to print it and then the carriage return key to start the next line. A modulo-8 counter is used to control the searching, the return zone having 8 character positions, but the capacity of the counter may be adjustable to effectively vary the width of the return zone.