;***************************************************************************   
;*                                                                         *
;*                                                                         *
;*                                                                         *
;*   This program programs the three counters to operate in three modes.   *
;*                                                                         *
;*                                                                         *
;***************************************************************************

 
 
;This demo program is used to demo the 8253x5 (programmable interval timer)
;This program programs the three counters in the 8253x5 to operate 
;in 3 of the 6 standard modes.
;The program follows.



        ORG     00H
        JMP     START 
        
        ORG     0CH
START:  LDA     40H   ;Load control word from memory.
        OUT     03H   ;Control word written to control word register.
        LDA     41H   ;Load control word from memory.
        OUT     03H   ;Control word written to control word register.
        LDA     42H   ;Load control word from memory. 
        OUT     03H   ;Control word written to control word register.

;       (* Writing initial count for counters. *)
        
        LDA     43H
        OUT     00H   ;load counter 0 with count value. 
        LDA     44H
        OUT     01H   ;load counter 1 with count value.
        LDA     45H
        OUT     02H   ;load counter 2 with count value.
        LDA     46H   ;delay loop
LOOP:   DCR     A 
        JNZ     LOOP
        HALT



;The following are memory locations and their contents.

          
        ORG     40H  
        DB      10H   ;control word for counter0 -- mode0.
        DB      56H   ;control word for counter1 -- mode3.
        DB      94H   ;control word for counter2 -- mode2.
        DB      04H   ;count value for counter 0
        DB      04H   ;count value for counter 1
        DB      03H   ;count value for counter 2
        DB      42H   ;load delay value.
        



