*****************
* Fragment DISPLAY - 6811
*
* This fragment is be included in routines requiring
* use of the 7-segment displays on the I/O box.
*
* Note that the calling program must specify the output port
* in location PORT (two bytes).  In most cases this will be
* $1004 (PORTB).
*
* The calling program must also specify the hi_byte, mid_byte
* and lo_byte in the lower nibble of locations HI_DIG, MID_DIG and
* LO_DIG.
*
* The program is placed at PSCT + $200.  It is the users responsibilty
* to avoid overlapping code.
*
* The routine is called using JSR DISPLAY. 
*
* All registers are saved on the stack and restored prior to
* exiting.
*
* See Program CHECKSUM for typical use.
*
* Peter H. Anderson, MSU, 14 Jan 90; Checked 16 Jan 90
*	   modified 5 Feb 90; Checked 5 Feb 91; 15 Jan 93
********************

	  ORG PSCT+$200
DISPLAY

	  PSHX			* save regs
	  PSHA

	  LDX PORT		* get port address

	  LDAA HI_DIG		*load hi_dig and output
	  ORAA #$F0
	  STAA 00,X
	  ANDA #$7F		* select latch
	  STAA 00,X
	  ORAA #$F0		* strobe
	  STAA 00,X

	  LDAA MID_DIG	 	* mid digit
	  ORAA #$F0
	  STAA 00,X
	  ANDA #$BF		* select latch
	  STAA 00,X
	  ORAA #$F0		* strobe
	  STAA 00,X

	  LDAA LO_DIG		* lo digit
	  ORAA #$F0
	  STAA 00,X
	  ANDA #$DF		* select latch
	  STAA 00,X
	  ORAA #$F0		* strobe
	  STAA 00,X

	  PULA			* restore regs
	  PULX

	  RTS