| 摘要 |
The addition-subtraction unit according to the subject of the invention has a main circuit 1 with nine individual adder circuits 12, and a one upwards shift circuit 6, which is combined with a straight-ahead circuit, and an exchange circuit 7, using which the result number of the one upwards shift circuit 6 is either passed straight on or increased by the number 5, if it is in the lower range 0 to 4, and either passed straight on or decreased by the number 5, if it is in the upper range 5 to 9. Subtractions are done additively, by processing the nine's complement of the subtrahend instead of the latter. <IMAGE>
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