What am I trying to do?
I am taking two integers from the user and trying to multiple them using mul instruction.
What is the problem?
Each time I try to multiple the 2 integers and try to display the result I get alphabet T as output.
data segment
msg1 db "Enter first number:$"
msg2 db 10, 13,"Enter second number:$"
msg3 db 10, 13,"The product is:$"
n1 db ?
n2 db ?
pkey db "press any key...$"
ends
stack segment
dw 128 dup(0)
ends
code segment
start: ; set segment registers: mov ax, data mov ds, ax mov es, ax
; add your code here
mov ax, @data
mov ds, ax
mov dx, offset msg1
mov ah,09h
int 21h
mov ah, 01h
int 21h
sub al, 48
mov n1, al
mov dx, offset msg2
mov ah, 09h
int 21h
mov ah, 01h
int 21h
sub al, 48
mov n2, al
mul n1
mov bl, al
mov dx, offset msg3
mov ah, 09h
int 21h
add bl, 48
mov dl, bl
mov ah, 02h
int 21h
mov ah, 4ch
int 21h
lea dx, pkey
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system. int 21h
ends
end start ; set entry point and stop the assembler.
Why do you get alphabet T as output ?
These instruction:
mov dx, offset msg3
mov ah, 09h
int 21h
causes the value of AL to be altered to 24 (Its actually INT 21h instruction which changes the value of AL to 24) and the instruction mov ah, 09h
sets the content of AH to 09. Then the next instruction
add ax, 48
add 48 to contents of AX which gives 84(54 in hex) in AL which is the ASCII value of T and then you display the contents of AL with the following code:
mov dl, al
mov ah, 02h
int 21h
which displays the alphabet T.
To fix it do the following:
After mul instruction add this:
mov bl, al ; save the content of AL to BL
and after displaying msg3
change occurrence of al to bl like this:
add bl, 48
mov dl, bl
mov ah, 02h
int 21h