| 摘要 |
<p>1,128,624. Size comparison. AUTOMATIC TELEPHONE & ELECTRIC CO Ltd. 23 Dec., 1965 [30 Dec., 1964], No. 52918/64. Heading G4A. In a digital data processing device in which the moduli of two signed data words A + B are compared for relative size, the state of a twostate switching device is controlled according to the algebraic sign of the resultant of the operations A + B and A-B. Thus, if the switching device is set for A+B positive, reset for A+B negative and has its state changed thereafter only if A-B is negative, then, if the switching device is finally in a set state A | # | B | and if the switching device is finally in a reset state | B |# | A | . The case in which | A | = ( B | is treated specially by monitoring for a zero result to the addition process (A and B of opposite sign) or subtraction process (A and B of same sign). An arrangement is shown in which the state of a bi-stable device TOF indicates the relative magnitude of the moduli of two binary words A and B which are added and subtracted by means not shown. The most significant bit of each word A and B indicates its sign and negative words are expressed in 2's complement form. The arrangement comprises a gating circuit including AND-gates GTS 1, GTS2, GS1, GS2, GR1, and GR2 and inverters ITS1 and ITS2. Gates GTS1 and 2 are controlled as indicated by signals indicating whether or not the signs of the words (AS and BS) _are equal and whether or not there is a carry (CS, CS) when the words are added or subtracted. These gates thus pass a signal only when the result of the addition or subtraction is positive. Signal SC is in its 1 state during the whole size comparison operation, signal A is 1 during the addition process and signal S is 1 during the subtraction step.</p> |
