*****************************************************************
*								* 
*    MORROW 68K SYSTEM clock routines				* 
*								*
*****************************************************************


*******************
*  E Q U A T E S  *
*******************

ioaddr	=	$ff0000			* compupro 68K i/o address space


base	=	ioaddr+$48		* standard base address
grpctl	=	base+$7			* select port
group0	=	8			* clock group select constant

clock	=	base+2			* clock address within group 0

tp64	=	$10			* constant for 64 Hz
clkstb	=	$20			* strobe inactive


****************************
*   B E G I N    C O D E   *
****************************

* Routine sets the interrupt rate to 64 time per second

setit:	move.b	group0,grpctl		* select group 0
	move.b	tp64,clock		* send 64 Hz constant strobe low
	nop				* stall for slow hardware
	nop				*   -minimum of 2.0 us
	nop				*   -for data setup time
	move.b	tp64+clkstb,clock	* send 64 Hz constant strobe high
	nop				* stall for slow hardware
	nop				*   -minimum of 2.0 us
	nop				*    -for data hold time
	move.b	tp64,clock		* send 64 Hz constant strobe low
	rts


* Routine clears the clock interrupt

clearit:
	move.b	group0,grpctl		* select group 0
	move.b	clock,d0		* read clock, clear interrupt
	rts

	.end