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1. Suppose EBX = 1000 (in decimal) and the unsigned decimal values of the bytes

ID: 3834582 • Letter: 1

Question

1.Suppose EBX = 1000 (in decimal) and the unsigned decimal values of the bytes stored in memory addresses 1000 through 1003 are 255, 255, 255, and 255. What effect do the following instructions have (independently) on this area of memory? For multi-byte data, assume the least significant byte is stored in the smallest address.

a.

Address

Before

After

1000

255

1001

255

1002

255

1003

255

b.

Address

Before

After

1000

255

1001

255

1002

255

1003

255

c.

Address

Before

After

1000

255

1001

255

1002

255

1003

255

Address

Before

After

1000

255

1001

255

1002

255

1003

255

Explanation / Answer

a. ADD BYTE PTR[EBX],1

Address Before After

1000 255 0

1001 255 255

1002 255 255

1003 255 255

b.ADD WORD PTR[EBX],1 Adress Before After

1000 255 0

1001 255 0

1002 255 255

1003 255 255

c.ADD DWORD PTR[EBX],1 Adress Before After

1000 255 0

1001 255 0

1002 255 0

1003 255 0