Assembler: I'm trying to use the Periodic Interrupt on the Real Time clock, what is wrong with my code?

Here is my code, written for the NASM assembler, with comments: (it probably won't look good on Yahoo! Answers, copy it into notepad/edit/other fixedwidth editor for the comments to align etc.)





[BITS 16]


org 0x0100





jmp start ; Jump to the start.





interrupt: ; interrupt to be called by the RTC





push ax ; push ax and


push dx ; dx onto stack


mov al,0x0c ; 0x0c into al to read the


out 0x70,al ; Status Register C in the RTC


in al,0x71 ; to reset it for the next interrupt


mov ah,0x02 ; DOS function 0x02 - write character


mov dl,0x41 ; "A"


int 0x21 ; DOS interrupt


pop dx ; pop dx and ax


pop ax ; back to their original values


iret ; return





start: ; Start of the main code





mov al,0x0b ; Select Status Register B


out 0x70,al


in al,0x71 ; Get the value


and al,10111111b ; Disable the Periodic Interrupt


out 0x71,al





mov al,0x0a ; Select Status Register A

Assembler: I'm trying to use the Periodic Interrupt on the Real Time clock, what is wrong with my code?
What happens when you run it? No output at all?

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