Question

Given that EAX contains FFFF80C0h, which of the following would be true after executing the CWD instruction?

a. AX=FFFFh, DX=80C0h
b. EDX=FFFFFFFFh, EAX=FFFF80C0h
c. DX=FFFFh, AX=80C0h
d. cannot be determined

Answer 1

Answer:

c. DX=FFFFh, AX=80C0h

Explanation:

CWD instruction set all bits in DX register with same sign as in AX register. The effect is to create a 32 bit sign result. This will have same integer value as of 16 bit.