PARTNO	  	XXXXX ;
		NAME	  	U4;
		DATE	  	August 30, 1991;
		REV		1 ;
		DESIGNER	Dave Haynie ;
		COMPANY		Commodore ;
		ASSEMBLY	A3000+ ;
		LOCATION	West Chester ;

/************************************************************************/
/*									*/
/*  A3000+ Gary+ Tower	Function Generator				*/
/*									*/
/************************************************************************/
/*  Allowable Target Device Types: 22V10-10	 			*/
/************************************************************************/
/*  Clock:		CLK90						*/
/************************************************************************/
/*  Free Pins:		13(I)						*/
/************************************************************************/
/*  HISTORY								*/
/*	DBH Aug 30:	Brand stinking new				*/
/************************************************************************/

/**  Inputs  **/

PIN 1		=  CLK90	;	/* System clock */
PIN 2		= !CIA1		; 	/* CIA selects */
PIN 3		= !CIA0		;
PIN 4		= !IKBRST	;	/* Incoming keyboard reset */
PIN 5		= !RSTREG	;	/* Register qualifiers */
PIN 6		= !DSPREG	;
PIN 7		= !NETREG	;
PIN 8		= !REGQUAL	;
PIN 9		=  RW		;	/* 68030 read/write strobe */
PIN 10		= !RST		;	/* I/O reset */
PIN 11		= !AS		;	/* 68030 address strobe */

/**  Outputs  **/

PIN 14		= !DSPRST	;	/* DSP reset output */
PIN 16		= !NETCS	;	/* Network chip select */
PIN 17		= !NETDS	;	    /* ... and data strobes */
PIN 18		=  VOVL		;	/* Virtual ROM overlay */
PIN 19		= !KBRST	;	/* Keyboard reset */
PIN 20		= !KBREN	;	/* Keyboard enable */

/**  Used Internally  **/

PIN 21		=  T0		;	/* Timer count */
PIN 22		=  T1		;
PIN 23		=  T2		;

/**  Declarations and Intermediate Variable Definitions  **/

/* Here are the fully qualified selects and all */

netsel		= NETREG & REGQUAL & AS;

dspsel		= DSPREG & REGQUAL & AS;

rstsel		= RSTREG &  REGRST & AS;

/**  Logic Equations **/

/* The DSP reset function responds to reset register writes. */

DSPRST		=  netsel & RW & !D0
		# DSPRST & !netsel;

DSPRST.SP	= !RST;

/* The data line reads back the DSPRST setting. */

D0		= DSPRST;
D0.OE		= DSPRST;

/* The network is selected and strobed here. */

NETCS		= netsel;

NETDS.D		= netsel;

NETDS.AC	= RST;

/* The virtual overlay function. *.

VOVL		=  RST
		# !RST & !CIA1 & !CIA2;

/* The keyboard stuff.  If KBENB is true, keyboard reset doesn't have to be
   aware of the underlying mechanisms. */

KBRST		= IKBRST & KBREN;

KBREN		=  RST
		# !RST & rstsel & AS & !D0
		# !RST & !rstsel & KBREN;
		 
/* The counter function.  */

/* The counters are responsible for measuring 200ns for Network Chip 
   select cycle termination. */

T0.D		= !T0 & !T1 & !T2 & AS
		# !T0 &  T1 & !T2 & AS
		# !T0 & !T1 &  T2 & AS

T1.D		=  T0 & !T1 & !T2 & AS
		# !T0 &  T1 & !T2 & AS
		
T2.D		=  T0 &  T1 & !T2 & AS
		#  T0 &  T1 &  T2 & AS