old/ASM/TIMER/TIMER.ASM

.model small
.code
ORG 100h
start:
        mov ax, 351ch
        int 21h

        mov ofs_1c, bx
        mov seg_1c, es

        mov ax, 251ch
        mov dx, offset int_1c
        int 21h

        mov ah, 31h
        mov dx, 50h
        int 21h

int_1c: 
	inc cnt
	cmp cnt, 39
	je wrt
        jmp     dword ptr ofs_1c
wrt:	push ax
	push bx
	push es
	mov cnt, 1
	mov ax,	0b800h
	mov es, ax
	mov bx,	from
	inc from
	mov bx,	[bx]
	mov es:[0], bx
	pop es
	pop bx
	pop ax
        jmp     dword ptr ofs_1c

cnt	db 0	
ofs_1c 	dw 0
seg_1c 	dw 0
from	dw 0
end start