90 lines
3.1 KiB
NASM
90 lines
3.1 KiB
NASM
|
; It will play 12 notes of the octave starting at middle C.
|
||
|
|
;-----------------------------------------------------------------------------
|
||
|
|
; How to generate sound on the IBM PC :
|
||
|
|
;
|
||
|
|
; The 8255 (port 61H) bit 0 controls the 8253 timer
|
||
|
|
; bit 1 controls the speaker
|
||
|
|
;
|
||
|
|
; The output channel 2 from the 8253 timer will be ANDed with the
|
||
|
|
; speaker control bit in order to turn on/off the speaker.
|
||
|
|
;
|
||
|
|
; Timer channel 2 internal count register (port 42h) is loaded in
|
||
|
|
; two successive OUT operations with the lower byte being loaded first.
|
||
|
|
; For this to work properly, timer command register has to be loaded first
|
||
|
|
; with B6H.
|
||
|
|
;
|
||
|
|
; Since the input clock to the timer chip is 1.19318 MHz, the counter value
|
||
|
|
; to generate the frequency X can be calculated by 1193180 / X.
|
||
|
|
;-----------------------------------------------------------------------------
|
||
|
|
; CX is used as a note counter with the frequency effectively being
|
||
|
|
; incremented by a half tone and the corresponding count being loaded
|
||
|
|
; into the count register on each iteration.
|
||
|
|
;
|
||
|
|
; No stack segment is needed for this small program, so don't panic
|
||
|
|
; when you receive the 'No stack segment' warning.
|
||
|
|
;
|
||
|
|
; Arne Asplem 880731 (MASM 4.0)
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
dseg segment ; data segment
|
||
|
|
notes dw 262,277,294,311,330,349,370,392,415,440,466,494
|
||
|
|
dseg ends
|
||
|
|
|
||
|
|
cseg segment
|
||
|
|
|
||
|
|
sound proc far
|
||
|
|
assume cs:cseg, ds:dseg, ss:nothing
|
||
|
|
|
||
|
|
start:
|
||
|
|
mov ax, dseg
|
||
|
|
mov ds, ax ; set up data segment (DS) reg.
|
||
|
|
xor si, si
|
||
|
|
mov bx, 12 ; note count
|
||
|
|
|
||
|
|
; set up timer command register and counter register
|
||
|
|
|
||
|
|
mov al, 0b6h ; set 8253 command register
|
||
|
|
out 43h, al ; for channel 2, mode 3
|
||
|
|
|
||
|
|
nloop:
|
||
|
|
mov ax, 34dch ; low part of clock freq.
|
||
|
|
mov dx, 12h ; hight part of clock freq.
|
||
|
|
div [notes + si] ; get note from data segment
|
||
|
|
out 42h, al ; 8253 command register (low byte)
|
||
|
|
mov al, ah
|
||
|
|
out 42h, al ; 8253 command regsieter (high byte)
|
||
|
|
|
||
|
|
; turn on low bits in 8255 output port
|
||
|
|
|
||
|
|
in al, 61h ; read current value of 8255 port
|
||
|
|
or al, 3 ; clear low bits
|
||
|
|
out 61h, al ; send new value to port
|
||
|
|
|
||
|
|
; loop while note is sounding
|
||
|
|
|
||
|
|
mov cx, 6d60h
|
||
|
|
|
||
|
|
rpta:
|
||
|
|
loop rpta ; 1/10 sec delay
|
||
|
|
|
||
|
|
; turn off speaker, check note count, set up next note
|
||
|
|
|
||
|
|
xor al, 3
|
||
|
|
out 61h, al ; turn off speaker
|
||
|
|
mov cx, 0af0h
|
||
|
|
|
||
|
|
rptb:
|
||
|
|
loop rptb ; 1/100 sec delay
|
||
|
|
inc si ; increment note pointer
|
||
|
|
inc si
|
||
|
|
dec bx ; decrement note counter
|
||
|
|
|
||
|
|
jnz nloop ; loop until bx = 0
|
||
|
|
|
||
|
|
mov ax, 4c00h ; terminate program
|
||
|
|
int 21h
|
||
|
|
|
||
|
|
sound endp
|
||
|
|
cseg ends
|
||
|
|
end start
|