;;  Emacs Mode Selection Info: -*-mode: ASM; coding: iso-latin-1-dos;-*- *
	;; ********************************************************************************************
	;; File Name:	Random.inc
	;; Auther:	John L. Weinrich
	;; Date:	01/31/03
	;; Useage	4004 TIC-TAC-TOE Game
	;; Description:	
	;; 
	;; This routine is used for the 4004 TIC-TAC-TOE Game. 
	;;
	;; Assumptions:
	;; This assembly code and all the included files assume the following:
	;; 
	;; RAM Memory:	2048 X 4 (8 RAM banks, 4 RAMs/bank, 4 registers/RAM, 16 Char/Reg)
	;;		256 status characters.
	;;		2 I/O Port
	;;			RAM1:	SPEAKER PITCH/write
	;;			RAM2:	SPEAKER LEVEL/write
	;; 
	;; ROM Memory:	4096 X 8 (16 ROMs @ 256 locations
	;;		11 I/O Ports (3 - R/W, 4- Read, 4 - Write)
	;;			ROM0:	MISC/read
	;;			ROM0:	MISC/write
	;;			ROM3:	DISPLAY HIGH IN/read
	;;			ROM3:	DISPLAY HIGH OUT/write
	;;			ROM4:	DISPLAY LOW IN/read
	;;			ROM4:	DISPLAY LOW OUT/write
	;;			ROM5:	KEYBOARD HIGH INPUT/read
	;;			ROM6:	KEYBOARD LOW INPUT/read
	;;			ROM7:	MISC2/write
	;;			ROM8:	PAGE/write
	;;			ROM9:	RANDOM NUMBER GENERATOR/read
	;;			ROM10:	FPGA VERSION/read
	;;
	;; See "4004 FPGA Design" and "4004 Software Design " documents for more detail information.
	;; 
	;; Registers used:	
	;; Memory used:		
	;; Entrance parameters:	
	;; Exit parameters:
	;; Labels used:		
	;; ********************************************************************************************
	
		;; Get random number
NewRandNum	ldm	RAM_BANK_0			; Select RAM bank 0
		dcl					; Send out RAM bank selection
		fim	SRC_P,RAND_NUM_GEN_PORT		; Select random number port
		src	SRC_P				; Send out port selection
		clb					; Make sure accumulator is clear
		rdr					; Get random number
		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		wrm					; Write random number to RAM
		clb					; Make sure accumulator is clear
		ldm	09h				; Get max numer
		sbm					; Subtract random number generator
		jcn	NC,NewRandNum			; Random number is not within range
		
		;; Check for position #1
		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	00h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos1			; Equal
		fim	UTILITY_1_P,POS1_RAM		; Select RAM game board position
		jun	Pos				; Position found

		;; Check for position #2
NotPos1		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	01h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos2			; Equal
		fim	UTILITY_1_P,POS2_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #3
NotPos2		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	02h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos3			; Equal
		fim	UTILITY_1_P,POS3_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #4
NotPos3		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	03h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos4			; Equal
		fim	UTILITY_1_P,POS4_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #5
NotPos4		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	04h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos5			; Equal
		fim	UTILITY_1_P,POS5_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #6
NotPos5		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	05h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos6			; Equal
		fim	UTILITY_1_P,POS6_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #7
NotPos6		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	06h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos7			; Equal
		fim	UTILITY_1_P,POS7_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #8
NotPos7		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	07h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos8			; Equal
		fim	UTILITY_1_P,POS8_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
		;; Check for position #9
NotPos8		fim	SRC_P,RNG_RAM			; Select random number RAM storage
		src	SRC_P				; Send out RAM selection
		clb					; Make sure accumulator is clear
		ldm	08h
		sbm					; Subtract random number to RAM
		jcn	NZ,NotPos9			; Equal
		fim	UTILITY_1_P,POS9_RAM		; Select RAM game board position
		jun	Pos				; Position found
	
NotPos9		jun	NewRandNum			; Position not found, try again

		;; Check to see if there is a X or O from a previous turn
Pos		src	UTILITY_1_P			; Tell RAM of selection of board number
		clb
		rdm					; Get position #1 RAM charactor
		jcn	NZ,NewRandNum			; Previous turn X or O
		bbl	REPORT_SUCCESS			; All done, report success