Addition: 9D 1D //all in hex BD 7D Subtraction: -11 6F 1F -31 Any explanation wo

Question

Addition: 9D 1D //all in hex BD 7D
Subtraction: -11 6F 1F -31
Any explanation would be great and I do give thumbs up for correct work. Thank you.

Does carry occur during any of the following (supposedly unsigned number) additions (8-bit adder)? (a) 4616+ 5116 (b) C66+ 5716 (c) E61+ C716 (d)2616+ 5716 Does overflow occur during any of the following (supposedly signed number) subtractions (8-bit adder)? (a) 4616-5716 (b) C616-5716 (c) E616-C716 (d) 2616-5716 Does carry occur during any of the following (supposedly unsigned number subtractions (8-bit adder)? (a) 4616- 5716 (b) C616- 5716 (c) E616- C716 (d)266-57

Explanation / Answer

1. The carry flag is set if the addition of two numbers causes a carry
out of the most significant (leftmost) bits added.

1111 + 0001 = 0000 (carry flag is turned on)

2. The carry (borrow) flag is also set if the subtraction of two numbers
requires a borrow into the most significant (leftmost) bits subtracted.

0000 - 0001 = 1111 (carry flag is turned on)

Otherwise, the carry flag is turned off (zero).
* 0111 + 0001 = 1000 (carry flag is turned off [zero])
* 1000 - 0001 = 0111 (carry flag is turned off [zero])

In unsigned arithmetic, watch the carry flag to detect errors.
In signed arithmetic, the carry flag tells you nothing interesting.

Overflow Flag
-------------

The rules for turning on the overflow flag in binary/integer math are two:

1. If the sum of two numbers with the sign bits off yields a result number
with the sign bit on, the "overflow" flag is turned on.

0100 + 0100 = 1000 (overflow flag is turned on)

2. If the sum of two numbers with the sign bits on yields a result number
with the sign bit off, the "overflow" flag is turned on.

1000 + 1000 = 0000 (overflow flag is turned on)

For Addition:
Carry occur in B and C cases

For subtraction
overflow occur for A and D cases

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