I need help with these two questions Especially the first on

I need help with these two questions! Especially the first one it confuses me a lot. Thanks

Indicate whether or not the jump happens (show work) a. MOV CL, 5 SUB AL, AL SHL AL, CL JNC LABEL1 b. MOV BH, 65H MOV AL, 48H OR AL, BH SHL AL, 1 JC LABEL1 Assume that array x has been loaded with 100 signed numbers. Write a program which copies the absolute value of each number in x into the corresponding location of y..data x db 100 dup (?) y db 100 dup (?).code; TO DO - place your code here

Solution

(1) a. Mov cl,5 ; it loads cl register with a number 5

sub al,al; subtracting one number with the same number results zero in that register al

shl al,cl; rotating al content cl times,since al contains zero, rotating o\'s cause zero in al register

jnc label 1; no carry, so jump doesn\'t take place.

Ans: No jump takes place for question 1 (a)

(b) mov bh,65; loads the number 65 into bh register, bh= 0110 0101b

mov al,48; loads the number 48 into al register, al= 0100 1000 b

or al,bh ; or operation between al & bh registers data which results al=6dh, or operation result is 1, if atleast one of the input is 1.

shl al,1 ; which shifts al content left side by 1 position, since msb of result is zero, so result is no carry.

jc label1; it doesn\'t jump to label1, because there is no carry .

Ans. 1 (b) Since the result of or operation has zero in msb, for left shift operation it results no carry.

2. .data

x db 100 dup (?)

y db 100 dup (?)

.code

start: mov ax,data; copy data into ax register

mov ds,ax; copy data in ax register to data segment register.

mov cx,100 ; take the count value into cx register

mov bx, offset x; copy address of array x into bx address register

mov al,[bx]; copy data in bx register content, i.e., array x into al register

xor al,al; xor opearation on al with al, to convert signed number to unsigned number

mov [si],al ; copy al register contents to si register address

mov di, offset y ; copy address of array y into di register

   cld ; auto-increment both si & di offset registers (address registers)

rep movsb; repeat until all elements of array x are copied to array y.

hlt ; terminate the program