Patent GB-748331-A (GB)
Title: Improvements in apparatus for converting numbers from one system of enumeration to another
Filed: 1950-10-05
Abstract: 748,331. Digital electric calculating-apparatus; counting-apparatus. EVANS, D. S. Oct. 5, 1951 [Oct. 5, 1950], No. 24382/50. Class 106 (1). Apparatus for converting a number from a first radix of rotation to a second, comprises a plural-stage pulse-counting device arranged to operate on the second radix, selector keys, one or more for each digit place of the highest number to be converted, each key closing a different electric switch or group of switches each adapted to connect one of a series of conductors to the input to one of the counting stages, means for supplying a voltage pulse to each conductor in turn when the appropriate selector keys have been actuated, and means for displaying the number registered on the counting device. In the decimal-to-binary converter shown in Fig. 1, units and tens sets of keys U0-U9, T0-T9 selectively operate sets of switches A-J connecting conductors 1A-1J respectively to the inputs of binary counting stages 2<SP>0</SP>-2<SP>6</SP>. A distributer 16 supplies a pulse to each conductor in turn owing to the successive charging and discharging of condenser 16d as rotary arm 16e moves over contacts 16a. Each counting stage may comprise a bistable trigger circuit (Fig. 2, not shown), similar to that described in Specification 707,371, and comprising two cross-connected valves the anode circuits of which are connected to output terminals 9<SP>0</SP>, 9<SP>0</SP>a ... 9<SP>6</SP>, 9<SP>6</SP>a, either of which may be connected by a switch 10<SP>0</SP> ... to output lead 11<SP>0</SP> ... for carry-over to the next higher counting stage. The state of each stage is indicated by a neon lamp (not shown). A negative number is entered by operating the keys in the usual way and changing over switches 10<SP>0</SP>-10<SP>6</SP> so that the binary complement is registered on the counter. In the binary-to-decimal converter shown in Fig. 3, keys BD1-BD7 corresponding to successive binary denominations are selectively operated to represent digits " 1 " and close switches to connect conductors 17-29 to inputs of units and tens counting devices CD1, CD2, each comprising four series-connected stages 2<SP>0</SP>-2<SP>3</SP> adapted for decimalcounting by feed-back connections 121, 12<SP>2</SP> operating stages 2<SP>1</SP>, 2<SP>2</SP> through delay circuits and rectifiers (not shown). The indicating neon lamps are replaced by electromagnetic relays 30-33 and 34-37, so connected that 31, 32 and 35, 36 are normally energized. These relays operate the contacts shown to supply current from batteries U38, T38 to one of ten lamps in each of the columns of windows UD0-UD9 and TD0-TD9. In another embodiment, for converting decimal fractions of a pound into shillings and pence, a keyboard and switch arrangement similar to that of Fig. 1 is combined with a counting and indicating arrangement similar to that of Fig. 3, but with counting devices operating in radices twelve and twenty. The counting devices may be also of electromechanical form, each binary stage comprising a pin wheel advanced by an electromagnetically-operated pawl-and-ratchet device, the pulse distributer 16 being replaced by a uni-selector. Transfer is effected by pivoted levers on the wheels co-operating with a fixed cam, and transfer down, corresponding to the feed-back over connections 121, 122, Fig. 3, by a rack operated by an electromagnet energized by transfer contacts associated with stage 2<SP>3</SP> to advance stage 2<SP>1</SP> three steps. The number registered may be indicated by numerals on the pin wheels or by lamps operated by a relay arrangement as described above, the relays being energized through contacts closed by projections on the wheels.