FakeError.asm

USE16
ORG 0x100
XOR AX,AX
INT 0x10    
mov cx,0x1C
; this code harvested from an old dos virus - makes a rat-a-tat sound on the PC speaker
new_shot:  
                push	cx			; Save the current count
		mov 	dx,0140h		; DX holds pitch
		mov   	bx,0100h		; BX holds shot duration
		in    	al,061h			; Read the speaker port
		and   	al,11111100b		; Turn off the speaker bit
fire_shot:	
                xor	al,2                    ; Toggle the speaker bit
		out	061h,al			; Write AL to speaker port
		add     dx,09248h		;
		mov	cl,3                    ;
		ror	dx,cl			; Figure out the delay time
		mov	cx,dx                   ;
		and	cx,01FFh                ;
		or	cx,10                   ;
shoot_pause:  
                                      loop	shoot_pause             ; Delay a bit
		dec	bx			; Are we done with the shot?
		jnz	fire_shot		; If not, pulse the speaker
		and   	al,11111100b		; Turn off the speaker bit
		out   	061h,al			; Write AL to speaker port
		mov   	bx,0002h                ; BX holds delay time (ticks)
		xor   	ah,ah			; Get time function
		int   	1Ah			; BIOS timer interrupt
		add   	bx,dx                   ; Add current time to delay
shoot_delay:  
                                       int 0x1A			; Get the time again
		cmp   	dx,bx			; Are we done yet?
		jne   	shoot_delay		; If not, keep checking
		pop	cx			; Restore the count
		loop	new_shot		; Do another shot

mov ax,1300h                   ; print string call
mov bx,0xFA                     ; attribute flag
mov cx,19h                    ; length of string 
xor dh,dh                       ; goddammit dosbox!
mov dl,0x85          ; start position
mov bp,si                     ; fill string area with bullshit 
int 0x10
mov dl,0x30        ; start position
int 0x10
; Delay then return to dos
xor ax,ax
int 1ah      ; get the time of day count
add  dx,111   ; this is a okay delay for what we are doing
mov bx,dx    ; store end of delay value in bx
again:                           
int 1ah
cmp dx,bx
 jne again
MOV AX,0x0003 
INT 0x10 
MOV AX,0x4C00 
INT 0x21