Patent GB-1152302-A (GB)
Title: Numerical Display System
IPC: G06F3/14
Filed: 1968-01-22
Abstract: 1,152,302. Suppression of insignificant zeros in numerical display systems. NIPPON COLUMBIA CO. Ltd. 22 Jan., 1968 [25 Jan., 1967], No. 3302/68. Heading G4H. A numerical display system comprises a plurality of numerical indicators, a register including a plurality of digit portions, and invalid zero indication control means, the arangement being such that the numerical indicators are sequentially and serially driven from the least significant digit indicator to the most significant digit indicator in synchronism with the sequential period of the register including a plurality of digit portions in which the numerical contents to be displayed are stored and digit-sequentially taken out therefrom in the manner of a right shift process, the contents of the register being displayed such that the invalid zero indication control means prevents the indicators from displaying an invalid zero or zeroes. Binary coded decimal data is held in register R, the least significant decimal digit being in location 1, the most significant being in location n and is shifted under control of clock pulses from a source U to decoders D0-D9 which drive the appropriate one of switching circuits 50-59 depending on the value of the digit being decoded. Each switching circuit is connected to the appropriate electrode of indicator lamps A1-A9. A decimal point counter L is connected to a decoder D5 to drive switch SS and the decimal point electrode t5 in each lamp. Clock pulses are also applied to a shift counter connected to decoders C1-Cn which via AND gates M1-Mn and switching circuits B1-Bn complete a circuit to a common electrode tp of each lamp so that each lamp is arranged to indicate in synchronism with the data being shifted out of the register R. The lamps can only indicate when the AND gates are enabled by a signal m from flip-flop J. Flip-flop I gives a signal il for the first circulation of register R and a signal il for the second and subsequent circulations. A counter G is operated to indicate how many significant digits exist in the member. The counter is reset to zero by a signal from AND gate K3 or from AND gate K4 during the first circulation of the register when the signal il occurs, the resetting effectively being performed by signals d0 or C1. During the first circulation the counter G is decremented by AND gate 122 which indicates when zeroes occur in any position other than the least significant position. During the second and subsequent circulations the counter is continuously decremented by pulses from AND gate K1. A decoder counts a signal when the counter G reaches " 1," the trailing edge of the pulse acting via AND gate K7 to reset flip-flop J, a pulse from Cn at the end of each circulation serving to set flip-flop J for the commencement of the next circulation. Thus if register R contains 000. . . 030021 then counter G is reset by the digits 2 and 3 and thus contains 5 at the end of the first circulation. On the second circulation the flip-flop J is reset by the trailing edge of the pulse produced at the count of 1 and thus displays digits 30021 and then suppress all other zeroes. An alternative circuit includes a decimal point display and in this version AND gate K4 receives an inputs P5, C1 and a signal dS from a decimal point decoder similar to the digit decoder D0-D9. This causes reset of the counter G whenever the decimal point occurs. Also gate K2 receives dS as input instead of C1.