#DEFINE PAGE0   BCF     H'03',5
#DEFINE PAGE1   BSF     H'03',5

OPSHUN  EQU H'81'       ;
PCL EQU H'02'       ;
STATUS  EQU H'03'       ;
PORTA   EQU H'05'       ;
TRISA   EQU H'85'       ;
PORTB   EQU H'06'       ;
TRISB   EQU H'86'       ;
INTCON  EQU H'0B'       ;



W   EQU 0       ;
F   EQU 1       ;
C   EQU 0       ;
DC  EQU 1       ;
COUNT1  EQU H'30'
COUNTER EQU H'31'


N   EQU D'12'
TEMP    EQU H'35'
Z   EQU 2

    ORG 0       ; Reset vector
    GOTO    5       ; Goto start of program
    ORG 4       ; Interrupt vector
    GOTO    5       ; Goto start of program
    ORG 5       ; Start of program memory

    CLRF    PORTA       ;
    CLRF    PORTB       ;


    PAGE1
    CLRF    TRISA       ;Port RA0 as output (see text)
    CLRF    TRISB       ;Port B0-B7 as output

    MOVLW   B'00000111' ;move zero into W (binary shown intentionally)
    MOVWF   OPSHUN      ;set into OPTION as timer ratio 1:2 (TMRO rate)


    PAGE0

    MOVLW   4   ;
    MOVWF   COUNTER ;

;--------------------------------------------------------------------------;




POLL    BTFSC   INTCON,2    ;
    CALL    ISR ;
    GOTO    POLL




;--------------------------------------------------------------------------;

ISR

    BCF INTCON,2    ;
    CLRF    PORTA
    MOVF    COUNTER,W
    CALL    TABLE
    MOVWF   PORTB

    MOVF    COUNTER,W
    CALL    SELECT
    MOVWF   PORTA
;--------   CALL    DEL_H--;

    DECFSZ  COUNTER
    GOTO    FIN
    MOVLW   h'4'
    MOVWF   COUNTER

FIN RETURN

;------------------------------------------------------------------------;



;------------------------------------------------------------------------------------------------;
;NUMBER TABLE;

TABLE   ADDWF   PCL,F       ;add to PCL
    RETLW   B'11000000' ;0  common anode codes
    RETLW   B'11111001' ;1
    RETLW   B'10100100' ;2
    RETLW   B'10110000' ;3
    RETLW   B'10011001' ;4
    RETLW   B'10010010' ;5
    RETLW   B'10000011' ;6
    RETLW   B'11111000' ;7
    RETLW   B'10000000' ;8
    RETLW   B'10011000' ;9



;---------------------------------------------------------------------------------;

SELECT  ADDWF   PCL,F
    NOP
    RETLW B'00000001'   ;0
    RETLW B'00000010'   ;1
    RETLW B'00000100'   ;2
    RETLW B'00001000'   ;3







;-----------------------------------------------------------------------;




DEL_H   MOVF    STATUS,W
    MOVWF   TEMP

    MOVLW   D'1'
    MOVWF   COUNT1

DELAY_1MS   MOVLW   N

D_LOOP  ADDLW   -1
    BTFSS   STATUS,Z
    GOTO    D_LOOP

    DECFSZ  COUNT1,f
    GOTO    DELAY_1MS

    MOVF    TEMP,W
    MOVWF   STATUS

    RETURN






;---------------------------------------------------------------------------;




    END         ;final line