| 摘要 |
The serial tetrad adder/subtracter according to the inventive subject matter has a tetrad adder/subtracter according to P 3328404.0, which can be switched over from addition to subtraction and from subtraction to addition. The effect of the additional circuit 5 is that H potential is applied to the correction circuit for subtracting the number 6 (LHHL) when in the case of addition the carry output y has L potential, and in the case of subtraction H potential. The circuit 7 is a conversion circuit from BCD 0 to BCD 6 and thus is attended by the same change of a four-digit BCD number (BCD 0 number) as an adder circuit for the number 6 (LHHL) when H potential is applied to it. Thus, the gate circuit 8 is set up in advance in the case of addition, and the gate circuit 9 in the case of subtraction. <IMAGE>
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