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In the last chapter we learned how an assembly language program is built. Now we move on to a higher level. The operators. MOV destination,source : lets say "mov ax,bx" ax will become the value which bx stores. ADD destination,count : lets say "add ax,bx" ax will be increased according to the value in bx - lets say ax = 10, bx = 2 then ax will become 12 (10+2) SUB destination,count : lets say "add ax,bx" ax will be decreased according to the value in bx - lets say ax = 10, bx = 2 then ax will become 8 (10-2) INC destination : lets say "inc ax" then ax will be ax+1 DEC destination : lets say "dec ax" then ax will be ax-1 AND destination,count : lets say "and ax,bx" then ax will be anded with bx, lets say ax = 1, bx = 0 then ax will be 0. OR destination,count : lets say "or ax,bx" then ax will be ored with bx, lets say ax = 1, bx = 0 then ax will be 1.
know after we learnt the basic command, what happened about the size of those registers well, you can't do one of those between registers which aren't not the same size : "mov ax,bl", "mov al,bx", "add cx,cl" and so on. simple example, if we want to preform subtraction, what will do, (before each example check if you can do it your self) : mov ax,20 ; ax will be 20 mov cx,10 ; cx will be 10 sub ax,cx ; ax will be 10 (ax-cx,20-10) know if we have a number in hex or bin and we want to put it as it is so we will have to put "h" after the number for hex and "b" for bin : mov ax,0a000h ; you must have a zero before a letter in hex mov ax,010010b ; a simple number in binary
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LESSON 2 Basic operations!!!!! |