; ************************************************
;	  Gun Fight at the MUN-88 Corale
;
;	       By Charles Robertson
;
;  Based on program number 94 from Science Fair
;  Microcomputer Trainer (Radio Shack)
;
; After running the program, the middle LEDs will
; rapidly blink on and off.  When the lights stop
; blinking, the first player to fire (by changing
; the DIP switches number 1 or 8) will win.  If
; you fire too soon, you will lose!
;
; ************************************************

	TITLE Gun Fight
MYSEG	SEGMENT
	ASSUME cs:MYSEG, ds:MYSEG, es:MYSEG

main:   mav ax, cs	; Set up the segments
	mov ds, ax
	mov es, ax

	mov al, ffh	; Clear the contents on the LEDs
	out 30h, al
	mov bl, al	; store value of LEDs in BL

	in al, 30       ; Read the DIP switch (to detect change)
	mov ah, al      ; Store value in AH

rep2:   mov dx, 2000h	; about 1/8th second
rep1:   in al, 30       ; Check to see if DIP has changed
	xor al, ah	; All bits should be the same (xor will be 0)
	jnz misfire     ; Bits are not the same - user fired early
	dec dx
	jnz rep1

	xor bl, 00011000	; Change pattern on LEDs
	mov al, bl		; Fetch pattern from BL
	out 30h, al

	dec cx
	jnz rep2

	mov al, 11100111       ; Show target pattern
	out 30H, al

rep3:   in al, 30h      ; wait for a user to respond
	xor al, ah	; xor will be 0 until a DIP is switched
	jz rep3

	cmp al, 10000000       ; Has player 1 won?
	je player1_wins

player2_wins:
	mov al, 11100110       ; Player 2 wins
	jmp done

player1_wins:
	mov al, 01100111       ; Player 1 wins
	jmp done

misfire:
	cmp al, 10000000       ; Did player 1 misfire?
	je player1_loses

player2_loses:
	mov al, 11111101       ; Player 2 fired too early
	jmp done

player1_loses:
	mov al, 10111111       ; Player 2 fired too early
	jmp done

done:   out 30h, al             ; Display final message
	int 6


MYSEG	ENDS
	END     main