Patent GB-731140-A (GB)
Title: Improvements in and relating to electric pulse counting and calculating apparatus
IPC: G06F7/52
Filed: 1953-10-15
Abstract: 731,140. Digital electric calculating apparatus. OLIVETTI & C. SOC. PER AZIONI, ING., C. Oct. 15, 1953 [Oct. 18, 1952], No. 28538/53. Class 106 (1). A pulse counting device comprises an accumulator having a plurality of two-condition elements, means for sequentially sensing the elements, and means, operable under the control of a pulse to be counted, to commutate an element just sensed when it is the first of the plurality showing a certain one of the two conditions. The pulse to be counted sets a flipflop 9, Fig. 3, into state II and prepares a gate 10 to pass a pulse o which is generated by a timing device 4 at the beginning of each cycle. This pulse sets a second flip-flop 11 into state II and also returns the flip-flop 9 to state I. The amount already counted (528,436 as shown in the Figure) is registered by magnetized spots on a track 1 which moves past a read/write head 2 and a write head 3. The timing device 4 produces a pulse d at the end of each denomination D1, D2, ... &c., and a pulse m at each possible spot position or " cell " (nine in each denomination). The output II of the flip-flop 11, and the m output from the timer 4, are applied to a gate 8 which opens only when the " read " amplifier 5 signals the first unfilled " cell ". An output pulse to " write " amplifier 6 causes that same cell to be " filled " immediately by the write head 2 and also restores the flip-flop 11 to its I condition. Carry-over. If all "cells" " of the first denomination are already filled the flip-flop 11 remains in condition II as the head 2 passes to the tens denomination D2. At this point a pulse d is passed through a gate 12, setting a flip-flop 13 to condition II. This causes the write head 3 to produce a series of negative signals erasing the spots registered in the units order. The process continues until the first unfilled cell is detected and filled as described above. Subtractive operation is brought about by polarity changers 7 and 14. When set by an " S " signal the device 7 reverses the polarities of signals passing through the amplifiers 5 and 6 so that the first filled cell which is detected causes the gate 8 to be opened and cancelling pulse from the amplifier 6 " erases " the spot. The head 3 subsequently fills all cells of a denomination which has been found by the head 2 to be completely empty. Although this process - does not keep the filled cells always at the extreme left of each section, the correct operation of the apparatus is not affected; Arrangements for eliminating this irregularity are mentioned. Calculations in accordance with the four rules can be performed by a second embodiment in which the equivalents of four decimal registers are provided by two magnetic tracks 16, Fig. 5, and 35, Fig. 6 (not shown), each track accommodating alternately the denominations of two registers. Thus, on the track 16, the units order IR1 of a register IR is followed by the units order AR1 of a second register AR; thence follow the tens orders IR2, AR2, &c. On the other track the orders of registers HR and TR alternate in a similar fashion. Addition. The register AR acts as the totalizer, in this case, and the amount to be added is registered in IR. During each scan of the track 16, the first filled cell found in each order of the register IR is emptied and a cell in the corresponding order of register AR is filled. When no unfilled cell is available in the AR order the entry is made in the next higher IR order and the AR order is emptied by the head 18. Subtraction of an item registered in IR from an amount in AR is carried out in a similar manner but with polarity-changing. devices 27, 32, 34a in operation. ' Multiplication and division are, based on the adding and subtracting processes described above and are performed by the well-known repeating methods, two further registers HR and TR. on a second magnetic track 35, Fig. 6 (not shown), being brought into use. The four available registers are employed as follows : " Column shifting" is accomplished by a stepwise movement, relative to its support, of the read/write head co-operating with the track 35 (Fig. 6, not shown). The multiplication process comprises the steps of periodically erasing one unit of the multiplier in TR1, of copying into IR the multiplicand read in HR, and then adding the multiplicand into AR. This process is repeated until each filled cell in TR1 has been emptied, whereupon the magnetic head is shifted one order to the right and the operation is resumed for each filled cell of TR2, and so on. The division process comprises the steps of periodically writing a unit into TR1, copying into IR the divisor read in HR, and then subtracting the divisor from AR. This process is repeated until an overdraft occurs in AR, whereupon the divisor is added back into AR during a period performed in accordance with the multiplying process. The magnetic head is then shifted one order to the right and the operation is resumed for each filled cell of TR2, and so on. Instead of registering data by spots on a magnetic track other devices such as gasdischarge counting tubes or Williams-type C.R.T. memory stores could be employed.