Not sure why you're asking if the code is correct. Does it perform the conversion you want? If it does then it's correct. If not then it isn't. If not, what isn't it doing; explain exactly what the problem is. Could you clarify what you mean by "convert ASCII to binary" with a couple of examples, for example A is 65 in ASCII, given input A would you want the program to display 0100 0001?
Also there are lots of different microprocessors each with its own assembly language. Which processor are you using?