GB1311688A - Calculating machines - Google Patents

Abstract

1311688 Calculating machine ADDMASTER CORP 29 April 1970 20640/70 Heading G4B A ten-key keyboard calculating machine includes a pin carriage which is indexed stepby-step as digits are set up order by order, and the add and subtract keys are arranged to shift the carriage by one further step to bring the lowest order setup digit into alignment with the units order of the printing and totalling mechanism prior to the add or subtract operation. The invention provides a further key, corresponding to a fraction of a unit, and means for preventing the carriage shift by one further step on depressing the add or subtract key if the further key has been used in setting up the number. As shown, the carriage 18, Fig. 8, after setting-up a number not containing a fraction, will come to rest with the units order of the number adjacent fraction printing wheel 34. Consequently, depression of add key 13 or subtract key 14, Fig. 10, is arranged to act through slide 65, stud 63, bellcrank 60, Fig. 7, and hook 57 to depress zero key 12a and thus shift the carriage one step to bring the units order of the number adjacent the units printing wheel 37. If, however, the number includes the fraction "¢", key 16 is depressed and through extensions 52, 53 and the "5" key, sets the "5" pin and shifts the carriage to bring the set "5" pin adjacent the fraction printing wheel 34. An extension 59 of a stem 54, also depressed the "¢" key, engages surface 90 to rock hook 57 clear of zero key extension 56 so that depression of the add or subtract key will not now result in any further shifting of the carriage. Depression of stem 54 by the "¢" key 16 results in a latch 82, Fig. 8, holding the stem 54 depressed until the carriage is returned to "home", stud 81 then triggering the latch. The latch 82 also holds stem 54 when the latter has been depressed by the add or subtract keys acting through hook 57; after its initial operation, therefore, hook 57 is held clear of extension 56, because of extension 59 co-acting with surface 90, and so repeated depressions of add key 13 can be made for repeated addition without further shifting of the carriage. The carriage may be shifted to deal with successively higher orders of the multiplier by use of the zero key. A "X" key (15), Figs. 1 and 2 (not shown) may be latched in depressed condition during this repeated addition to disable the carriage return mechanism 52, 96, 54, 78, Fig. 8. The hook 57 is also held clear of extensions 56, 59 when the carriage is in its "home" position by linkage, Fig. 3 (not shown); totalling operations via keys 13, 14 are thus permitted.