# Sound

I'm really, really new to assembly. So, can anyone teach me how to play any sound using turbo assembly. My prof tells us that we can be able to do this, but he can't teach us how beacuse of time constraints. Just curious.

• : I'm really, really new to assembly. So, can anyone teach me how to play any sound using turbo assembly. My prof tells us that we can be able to do this, but he can't teach us how beacuse of time constraints. Just curious.
:

>> You can try searh on the net
Well basically sound uses port 61h, it ins an outs to that port.

• Here's a cheap snippet off the top of my head (not tested):
[code]
;Assemble into a .COM file using NASM.
;This program takes a Hertzian frequency specified on the command line
;and plays it over the internal speaker until the user presses a key.
EnableSpeaker equ 00000011b
DisableSpeaker equ 11111100b
CommandLine equ 81h
PIT_Frequency equ 1193182 ;Hz
SetupPIT equ 00110110b

Start:
mov si,CommandLine

;This takes in a decimal number in ASCII pointed to by DS:SI and
;converts it to hex so that it can be processed.
ConvertASCIIDecToHex:
cld ;Make string instructions work in a forwards direction.
mov bp,10 ;Destination base.
xor bx,bx ;This will hold the hex number as it comes in.

ConvertLoop:
lodsb
xor dx,dx ;No numbers above 65535 are up for conversion (used in MUL).
cmp al,"0"
jb PlayFrequency
cmp al,"9"
ja PlayFrequency
sub al,"0" ;By doing this, the ASCII digit will be converted into a useable number.
movzx cx,al ;Same as XOR CH,CH and MOV CL,AL.
mov ax,bx
mul bp ;Make room for the new digit by doing DX:AX = AX * BP
mov bx,ax ;Save the result into the "container".
test dx,dx ;This checks if DX is zero or not.
jz ConvertLoop ;If not, the number is too large. If so, loop.

IncorrectNumberRange:
mov ah,9
mov dx,WrongNum
int 21h
int 20h

WrongNum db "The input frequency entered on the command line must be between 65536 and 0!\$"

PlayFrequency: ;Can't do it just yet. Need to do a calculation first.
test bx,bx ;A divide by zero would not be good!
jz IncorrectNumberRange

in al,61h
or al,EnableSpeaker
out 61h,al
mov al,SetupPIT ;Set up the PIT for what's being done.
out 43h,al

mov dx,(PIT_Frequency>>16) ;Get high word into DX.
mov ax,(PIT_Frequency & ((1<<16)-1)) ;Put low word into AX.
div bx ;AX r DX = DX:AX / BX
;You could round the frequency, but I'm not going to.

out 42h,al ;Send the LSB.
mov al,ah
out 42h,al ;Then the MSB.

xor ah,ah ;Wait for a keypress before continuing (the key will simply

in al,61h
and al,DisableSpeaker
out 61h,al

int 20h
[/code]