For all instruction with using immediate values as an operand for to write the value into a ram location (or for calculating within), we have to specify how many bytes we want to access. Because our assemble can not know if we want access only one byte, a word, or a doppleword for example if the immediate value is a lower value, like the following instructions shows.
array db 0FFh, 0FFh, 0FFh, 0FFhmov byte [array], 3results:
array db 03h, 0FFh, 0FFh, 0FFh....
mov word [array], 3results:
array db 03h, 00h, 0FFh, 0FFh....
mov dword [array], 3results:
array db 03h, 00h, 00h, 00hDirk