;this program waits for user input. if the user presses '1' it outputs a string, if '2' it exits
.model small
.stack 100h
.data

doHz = 2280
reHz = 2031
miHz = 1810
faHz = 1708
solHz = 1522
laHz = 1356
siHz = 1208
pause dw ?
pause1 dw ?

.code      
init:   mov ax,@data       ;initialize data sector
        mov ds,ax
        mov ax,3           ;initialize video mode: text
        int 10h
        
top:    in al,64h          ;check port 64 - do nothing
        AND al,1           ;if no keys are pressed
        cmp al,1        
        jne top
        
        in al,60h          ;read in key pressed
        cmp al,2      
        je goDo
        cmp al,3      
        je goRe
        cmp al,4      
        je goMi
        cmp al,5      
        je goFa
        cmp al,6      
        je goSol
        cmp al,7      
        je goLa 
        cmp al,8      
        je goSi
        
        cmp al,9           ;exit condition - key '8'
        je fin
        jmp top            ;no conditions are matched
        
goDo:   call do
        jmp top
goRe:   call re
        jmp top
goMi:   call mi
        jmp top
goFa:   call fa
        jmp top
goSol:  call sol
        jmp top
goLa:   call la
        jmp top
goSi:   call siH
        jmp top
                                        
fin:
mov ah,4ch                ;return control to OS
    int 21h
;*************************
wait1: mov pause,0ffh
agn1:  mov pause1,0ffh
agn2:  dec pause1
       jnz agn2
       dec pause
       jnz agn1
    ret
;*************************
do:     mov ax,doHz
        out 42h,al         ;set sound to DO
        mov al,ah
        out 42h,al
        
        call output
    ret        
;*************************
re:     mov ax,reHz
        out 42h,al         ;set sound to RE
        mov al,ah
        out 42h,al
        
        call output
    ret        
;*************************
mi:     mov ax,miHz
        out 42h,al         ;set sound to MI
        mov al,ah
        out 42h,al
        
        call output
    ret       
;*************************
fa:     mov ax,faHz
        out 42h,al         ;set sound to FA
        mov al,ah
        out 42h,al
        
        call output
    ret        
;*************************
sol:    mov ax,solHz
        out 42h,al         ;set sound to SOL
        mov al,ah
        out 42h,al
        
        call output
    ret        
;*************************
la:     mov ax,laHz
        out 42h,al         ;set sound to LA
        mov al,ah
        out 42h,al
        
        call output
    ret        
;*************************
siH:    mov ax,siHz
        out 42h,al         ;set sound to SI
        mov al,ah
        out 42h,al
        
        call output 
    ret        
;*************************
output:
        in al,61h
        OR al,00000011     ;set 61h port to output sound
        out 61h,al
        
        call wait1
        
        in al,61h
        AND al,11111100b   ;set 61h port to output sound
        out 61h,al
    ret                         
end