GB1476953A - Scientific calculator - Google Patents

Abstract

1476953 Timing apparatus HEWLETTPACKARD CO 30 April 1974 [29 May 1973] 46148/76 Divided out of 1476951 Heading G3T [Also in Division G4] The description forms part of that of Specification 1476951 from which this application is divided but the claims are directed to the calculator when used in its clock mode i.e. either as a clock or as a stop watch. The clock mode is initiated by pressing the recall key RCL 118 Fig. 1, followed by the enter key 116, a time being entered with the digits displayed on a light emitter diode display to the left of the decimal point representing hours, the first two digits to the right representing minutes, the next two digits representing seconds and the last two digits representing hundredths of seconds. Operation of a change sign key CHS and an enter exponent key EEX toggles the clock and blanks/ unblanks the hundredths of a second display respectively. The summation key stops the clock and it is zeroed by operation of a clear X key CLX. Split times are stored by operating a digit key which results in a time being stored in a storage register of the same number as the digit of the pressed key. Consequently the calculator may be used as a stop watch for a race by pressing digit keys as each competitor crosses the finish line. Further operation of digit key recalls the stored times. The clock mode is based on the fact that the hundredths of a second count should be incremented every 35 instructions so that in the clock mode each programme loop Fig. 4 (not shown) is made after 35 instructions in length by including a loop dependent delay with no-op code or other instructions not related to operation of the clock. Specifications 1476952 and 1476954 are referred to.