Patent GB-1289148-A (GB)
IPC: G06F3/153
Filed: 1969-10-23
Abstract: 1289148 Cathode-ray tube displays TELEFUNKEN PATENTVERWERTUNGS GmbH 23 Oct 1969 [23 Oct 1968] 52079/69 Heading H4T In an arrangement in which coded items of information are called up from a store to a unit in which processing of the items of information requires periods of time which vary in length in accordance with the content of such items, the call up is effected by means which, in response to the contents of the called up items, produces time marker pulses indicating the ends of the processing periods and acting as call up pulses for the next item of information. The invention is described in connection with an Alpha- Numeric cathode-ray tube display in which different operations require different amounts of time, e.g. moving the beam to an initial position requires more time than the movement of the beam between adjacent characters in a line of characters and the tracing of corrected vectors, after the first requires less time than characters since the co-ordinates of the end point of first vector are also the co-ordinates of the start point of the second vector &c. Fig. 1 shows the described embodiment in which coded items of information in the form of hexad data bits derived from a computer store RS and supplied over channel SK to a display cathode-ray tube arrangement SG which includes character generating and vector tracing control circuitry. The channel SK includes a register R1 which holds the hexad bits for a specific moment during transmission and then passes them on in parallel form to the arrangement SG. Whilst the bits are in register R1 and when a gate T1 is open, a similar bit pattern is set up in a register R2 forming part of a recognition circuit ES which includes a decoding material EM. The latter in response to the coded bit pattern energizes output lines E when an Alpha- Numeric character is to be traced and output lines E<SP>1</SP> when vectors are to be traced. These lines energize pre-selected input lines of a programme matrix PM and additionally operate via an OR gate D to open a gate T2 which passes , clock pulses from a generator TG to a sequence chain K comprising M bi-stable elements. The latter are so connected to the matrix PM that the setting inputs of any selected element may be energized from the output of any other element so that e.g., a "1" can travel in any direction and can "skip" any predetermined element or elements and the output off each element are connected to selected output lines of the matrix, e.g., AL, SRL and SL. The output on the latter lines thus comprises pulse, trains having a selectable number of pulses and time intervals between individual pulses, the last pulse of which is always produced by the setting of the nth bistable element K. This last pulse occurs on line SRL and is utilized to re-set bi-stables F1 and F3 and the occurrence of a pulse on line AL indicates that sufficient time has elapsed for the processing of the last item of information received to be completed. Such pulse is then operative via a priority unit VW to call-ap the next item of information. Only selected hexads are employed to prepare a pulse programme the pulses of which call-up other hexads concerned with the actual positioning of the tube beam or the tracing of a particular form of character, vector &c. and operation of the arrangement by such other hexads is prevented by a pulse on line SL which closes gate T1. The operation of the arrangement in response to received data concerned with displaying two characters followed by two vectors is described with reference to Fig. 2 (not shown).