Write a TSR to generate the pattern of the frequency tones by reading the Real Time Clock (RTC). The duration of the each tone is solely decided by the programmer.

                                        Savitribai Phule Pune University
                            Second Year of Computer Engineering (2015 Course)
                                                     210257: Microprocessor Lab
                                                                Assignment No.13

Problem Statement: Write a TSR to generate the pattern of the frequency tones by reading the Real Time Clock (RTC). The duration of the each tone is solely decided by the programmer.  

;*************************************************************

code segment
assume cs:code
org 100h                ;prog seg prefix addrss
jmp initze              ;hex no of 256
savint dd ?             ;for saving address of es:bx
count dw 0000h          ;count of tics

hours db ?
mins db ?
sec db ?

testnum:
        push ax    ;store all the contents of register
        push bx    ;(not to change original values of register)
        push cx
        push dx
        push cs
        push es
        push si
        push di

        mov ax,0b800h   ;starting address of display
        mov es,ax
        mov cx,count
        inc cx
        mov count,cx
        cmp cx,011h
      
      jne exit

        mov cx,0000h
        mov count,cx
        call time
exit:
        pop di
        pop si
        pop es
        pop ds
        pop dx
        pop cx
        pop bx
        pop ax
        jmp cs:savint   ;jump to normal isr

;------------------convert procedure--------------------
convert proc
        and al,0f0h
        ror al,4
        add al,30h
        call disp
        mov al,dh
        and al,0fh
        add al,30h
        call disp
        ret
endp

;------------------------time procedure----------------
time proc
        mov ah,02h      ;getting current time system clk
        int 1ah
        mov hours,ch    ;HH->ch, MM->cl, SS->dh
        mov mins,cl
        mov sec,dh

       ; mov bx,0E00h    ;location for displaying clk
  
       mov bx,3984
        mov al,hours       ;Display Hours
        mov dh,hours
        call convert
        mov al,':'
        call disp

        mov al,mins       ;Display Mins
        mov dh,mins
        call convert
        mov al,':'
        call disp


        mov al,sec       ;Display Seconds
        mov dh,sec
        call convert
    
       call tone
 
       ret
         endp


;-----------------------display procedue----------------
disp proc
        mov ah,9Ch      ;for setting attribute
                 ;ATTRIBUTE BYTE  BL  R  G  B  I  R  G  B  
                                         ;BACKGROUND FOREGROUND
       mov es:bx,ax    ;write into vedio buffer
        inc bx
        inc bx
        ret
endp

;--------------- frequency tone procedure-------------------

tone proc

       mov     al, 182         ; Prepare the speaker for the
        out     43h, al         ;  note.
        mov     ax, 4560        ; Frequency number (in decimal)                              
        out     42h, al         ; Output low byte.
        mov     al, ah          ; Output high byte.
        out     42h, al
        in      al, 61h         ; Turn on note (get value from
                                ;  port 61h).
        or      al, 00000011b   ; Set bits 1 and 0.
        out     61h, al         ; Send new value.
        mov     bx, 25          ; Pause for duration of note.
.pause1:
        mov     cx, 65535
.pause2:
        dec     cx
        jne     .pause2
        dec     bx
        jne     .pause1
        in      al, 61h         ; Turn off note (get value from
                                ;  port 61h).
        and     al, 11111100b   ; Reset bits 1 and 0.
        out     61h, al         ; Send new value.  
       ret
endp
;------------------initialization------------------------
initze:
        push cs
        pop ds
        cli             ;clear int flag

        mov ah,35h      ;35 for get orignal add
        mov al,08h      ;intrrupt no
        int 21h
        mov word ptr savint,bx
        mov word ptr savint+2,es

        mov ah,25h              ;25 for set int add
        mov al,08h
        mov dx,offset testnum   ;new add for intrrupt
        int 21h

        mov ah,31h              ;make prog resident(request tsr)
        mov dx,offset initze    ;size of program

        sti                    ;set intrrupt flag
        int 21h               
code ends
end