| 摘要 |
<p>852,388. Digital electrical calculating apparatus. WESTERN ELECTRIC CO. Inc. Nov. 25, 1958 [Dec. 3, 1957], No. 37887/58. Class 106(1). A network for determining the magnitude and sign of the difference between two numbers, one expressed in conventional binary code and the other in reflected binary code, comprises a comparison circuit for each denomination and control means comprising more than two carry leads connecting each comparison circuit other than that associated with the least significant digit position with output means associated with the next less significant digit position. The minuend is entered on leads g A , g B ... g N in conventional binary code and the subtrahend on leads b A , b B ... b N in reflected binary code. Taking the comparison circuit N-1 as an example the following rules then apply: 1. If the inputs on g N-1 and b N-1 are both zero the AND gates 325, 330 produce no outputs and the positive carry leads 341, 356 and the negative carry leads 122, 123 bear the same signal as was applied to them from the preceding position. 2. If the signal on g N-1 is zero and that on b N-1 is one then both carry leads of one polarity will be energized. All outputs, such as - R N , + R N of the same polarity in less significant digit positions will be energized so long as all less-significant digits are zero. A less-significant one on a " g " input inhibits one output in its position, over circuit 335 or 385 according to sign. Similarly a less-significant one on a " b " input stops one of the carry signals so preventing an output in that and succeeding digit positions. This carry will be restarted if another one appears on a " b " input in a subsequent position. 3. If the signal on g N-1 is one and on b N-1 is zero two carries of the opposite polarity will be started. These carries are continued through successive positions as long as the " g " inputs are one and the " b inputs are zero. The appearance of a zero " g " input inhibits one output in that position. The appearance of a one " b " input stops one carry and one output in that and all subsequent positions. Another one " b " input restarts the carry. 4. If the signals on both g N-1 and b N-1 are one and no mismatch in an earlier position has occurred there are no outputs and no carries and the reflected binary code input digit on the next " b " terminal is reversed. Output circuit. When a comparison circuit has an output it applies a potential to one or more associated resistors - R N-1 , + R N + 1 . weighted according to the binary position concerned. There is an additional pair of resistors - R o , + R o of unit weighting. The resultant currents are accumulated and applied to output terminals prior to conversion to digital form in known manner. Specifications 663,872, 843,723 and 850,503 are referred to.</p> |
