In order to say the compiler about data type, these prefixes should
be used:
BYTE PTR - for byte.
WORD PTR - for word (two bytes).
For example:
BYTE PTR [BX] ; byte access.
or
WORD PTR [BX] ; word access.
MicroAsm supports shorter prefixes as well:
b. - for BYTE PTR
w. - for WORD PTR
Sometimes compiler can calculate the data type automatically, but
you may not and should not rely on that when one of the operands is an
immediate value.
MOV instruction
· Copies the second operand (source) to the first operand
(destination).
· The source operand can be an immediate value, general-purpose
register or memory location.
· The destination register can be a general-purpose register, or
memory location.
· Both operands must be the same size, which can be a byte or a
word.