GB1143203A - Improvements in or relating to calculating machines - Google Patents

Abstract

1,143,203. Electronic calculators. BELL PUNCH CO. Ltd. 12 May, 1966 [12 May, 1965], No. 20075/65. Heading G4A. An electronic calculating machine includes means for converting the decimal fractional part of a value expressed as a first number in decimal rotation of a first unit into the said part of a value expressed as a second number in a second smaller unit. As described, a keyboard-operated electronic calculator with provision for the four rules of arithmetic of the type disclosed in Specification 1,042,785 and also with provision for dealing with and indicating the position of the decimal point as disclosed in Specification 1,042,787 is further provided with built-in circuitry for performing the following operations (i) converting from decimal pounds to ú s. d. (ii) converting pennies into shillings and decimal fractions of a shilling (i.e. dividing by 12) and (iii) converting decimal shillings into pounds and decimal fractions thereof (dividing by 20). The first operation involves multiplying the decimal fractional part of a number in the R-register (Fig. 1, not shown) by 20 as far as the decimal point (detected by DEC 11 lead from decimal point counter DC in Fig. 2, not shown, to gate TR5U in Fig. 5, not shown) then multiplying the result by 12 as far as the third digit below the decimal point (detected by DEC 11 connection to TR5L gate in Fig. 5, not shown). The multiplication factors (12, 20, 1/12, 1/20) are generated by gates SG1-SG7 (Fig. 4, not shown), selected ones of which are enabled when one of keyboard switches L, S or D (Fig. 3, not shown, corresponding to operations i, iii and ii respectively) is operated, the timing signals connected to the different gates being such as to produce the required string of pulses for the multiplication involved (e.g. .0833... 34 for 1/12).