Which value does EDX have after logic NEG and AND instructions?

Question

I'm solving one of the assembler questions and I stumbled upon one with logic aspect. The thing that makes me thinking is that after changing the numeral system from HEX to BIN and making a negation and AND operations I got a different answer than other person (which I cannot contact).

MOV eax, 0f0f0f0f0h;
MOV edx, 87654321h;
NOT ax;
INC dx;
AND edx, eax;

I was expecting an output to be like this: 80604020h which is one of the answers, but the other person made a decision and answered: 80600302h which for me doesn't make a sense after doing the math. I'm still new in assembly so I may not know what is wrong, can someone explain what is wrong with my answer, or is it a correct one?

Answer 1

Let's take this one instruction at a time. The NOT ax will change EAX from

0F0F0F0F0

to

0F0F00F0F

since AX is the lower 16 bits of EAX. Then the INC dx will change EDX from

 87654321

to

 87654322

The AND edx,eax instruction will then combine them

 0F0F00F0F
& 87654322
= 80600302

Which makes your friend's answer correct.

If the NOT instruction was NOT EAX , then the answer would be 07050302.