Using byte registers with dword registers
•Task:
•Suppose we have a value in AL (a byte value).
•We don’t know what other parts of EAX contain.
•We want to add this value to ECX.
•
•Solution:
•
•EBX := AL    or   EAX := AL
•ECX := ECX + EBX ECX := ECX + EAX
•
•We can use:
•MOV  BL, AL
•MOV  byte ptr [b], AL    ; in C language: static bool b = func() 
•
•We cannot use:
•MOV EBX, AL  ; operand size conflict