Type Conversion
Name Description Code Operation operands operand size
cbw Convert byte to word cbw AX = AL (signed)    
cwde Convert word to doubleword in EAX register cwde EAX = AX (signed)
cwd Convert word to doubleword cwd DX:AX = AX (signed)
cdq Convert doubleword to quadword cdq edx:eax = eax (signed)
movsx

Move and sign extend

movsx dest,source dest = source (signed) reg, reg
reg, mem

word, byte
dword, byte
dword, word

movzx Move and zero extend movzx dest,source dest = source (unsigned)