Category : Assembly Language Source Code
Archive   : ZAD.ZIP
Filename : ZADEX.SRC

;This EXAMPLE PROGRAM is meant to illustrate the use of
;pseudo-ops in assembly language programming and has no
;other function or purpose.

;-------DEFINITION OF CONSTANTS------------------------
;
OUTCDE EQU 80H ;OUTPUT CNTL CODE FOR 8255A
CNTLPT EQU 0C3H ;CONTROL PORT ADDRESS
DATAPT EQU 0C0H ;DATA PORT ADDRESS
TIMECN EQU 100D ;100MS TIME CONSTANT

;-------LINKAGES TO SUBROUTINES------------------------
;
DELAY EQU 0FFDH ;LINKAGE TO DELAY SUBROUTINE
MESOUT EQU 0FF4H ;LINKAGE TO MESSAGE SUBROUTINE

;-------PROGRAM STARTS HERE----------------------------
ORG 1800H ;PROGRAM LOAD ADDRESS

START: LD A,OUTCDE ;LOAD CNTL CODE FOR OUTPUT
OUT (CNTLPT),A ;TRANSMIT CNTL CODE TO 8255A
LD C,10D ;INIT LOOP1 INDEX
LD HL,TBSTRT ;POINT HL TO START OF TABLE
LD (STORE),HL ;SAVE POINTER IN MEMORY

LOOP1: LD A,10000001B ;INIT LAMP PATTERN FOR LEDS
OUT (DATAPT),A ;TRANSMIT LED DATA TO 8255A
LD HL,TIMECN ;INIT HL WITH TIME CONSTANT
CALL DELAY ;EXECUTE 100MS DELAY
XOR A ;CLEAR ACC
OUT (DATAPT),A ;TURN OFF LEDS AFTER DELAY

LD B,TBEND-TBSTRT ;INIT LOOP2 INDEX
LD HL,(STORE) ;POINT TO BEGN OF TABLE
LOOP2: LD A,(HL) ;GET A BYTE
OUT (DATAPT),A ;OUTPUT IT TO PORT
INC HL ;ADV DATA POINTER
DJNZ LOOP2 ;REPEAT UNTIL ALL BYTES OUT

DEC C ;ADJUST LOOP1 INDEX
JP NZ,LOOP1 ;REPEAT UNTIL 10 LOOPS DONE

LD HL,MESG ;POINT TO "DONE" MESSAGE
CALL MESOUT ;TRANSMIT IT TO DISPLAY
HALT ;FINISHED WITH PROGRAM

STORE: DEFS 2 ;ALLOCATE TWO BYTES FOR --
; STORAGE OF TABLE PNTR

;-------DATA AND MESSAGES------------------------------
;
TBSTRT: DEFB 12H,5AH,0D5H,0FFH,4EH,01H ;DATA TABLE
TBEND: ;END ADR OF TABLE
MESG: DEFM 'DONE ' ;MESSAGE STORAGE