;This is the program to find out the square root of the 
;given 8-bit number by traditional shift & sub method.
;The number is logically extended to 16-bit number & 
;is stored in r0 & r1.The final answer is stored in
;r2.The 8-bit number will have 4-bit square rooot.
        numh equ 0
        numl equ 1
        sqrt equ 2
        sub equ 3
        cntr equ 4
        org 100h
        ;initialisation. 
        mov numh,#0
        mov numl,#121
        mov sqrt,#0
        mov cntr,#4
        ;main loop.
    bck:mov a,sqrt;
        clr c;
        rlc a;
        setb c;
        rlc a;
        mov sub,a;sub=sqrt<<2.
        ;num=num<<2.
        clr c;
        mov a,numl;
        rlc a;
        mov numl,a
        mov a,numh;
        rlc a;
        mov numh,a;
        clr c;
        mov a,numl;
        rlc a;
        mov numl,a;
        mov a,numh;
        rlc a;
        mov numh,a;
        ;numh=numh-sub.
        clr c;
        subb a,sub;
        jc  skip;if negative, skip.
        mov numh,a;else store the result.
        ;sqrt=sqrt<<1.
   skip:mov a,sqrt;
        cpl c;if answer is neg. pad lsb with 0.
        ;else pad with 1.
        rlc a;
        mov sqrt,a;
        djnz cntr,bck;loop back till the counter is exhausted.
        nop
        end