One way to make a four-bit adder perform subtraction is by: inverting the output

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Question
One way to make a four-bit adder perform subtraction is by:
Options
A. inverting the output.
B. inverting the carry-in.
C. inverting the B inputs.
D. grounding the B inputs.

Correct Answer

inverting the B inputs.

Digital Arithmetic Operations and Circuits problems

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3. Fast-look-ahead carry circuits found in most 4-bit full-adder circuits:
Options
A. determine sign and magnitude
B. reduce propagation delay
C. add a 1 to complemented inputs
D. increase ripple delay

5. Which of the following is the primary advantage of using binary-coded decimal (BCD) instead of straight binary coding?
Options
A. Fewer bits are required to represent a decimal number with the BCD code.
B. BCD codes are easily converted from decimal.
C. the relative ease of converting to and from decimal
D. BCD codes are easily converted to straight binary codes.

6. The two's-complement system is to be used to add the signed numbers 11110010 and 11110011. Determine, in decimal, the sign and value of each number and their sum.
Options
A. ?14 and ?13, ?27
B. ?113 and ?114, 227
C. ?27 and ?13, 40
D. ?11 and ?16, ?27

9. Convert each of the following signed binary numbers (two's-complement) to a signed decimal number.
00000101 11111100 11111000
Options
A. ?5 +4 +8
B. +5 ?4 ?8
C. ?5 +252 +248
D. +5 ?252 ?248

10. Subtract the following binary numbers.

0101 1000 1010 0011 1101 1110

?0010 0011 ?0011 1000 ?0101 0111
Options
A. 0011 0100 0110 1010 1000 0110
B. 0011 0101 0110 1011 1000 0111
C. 0011 0101 0110 1010 1000 0111
D. 0011 0101 0110 1010 1000 0110

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