; FILL - BYTE FILL
; 
;      THIS IS ONE OF A SET OF BYTE MANIPULATION ROUTINES IN WHICH THE
; BEGINNING OF A STRING IS SPECIFIED BY AN ADDRESS,COUNT PAIR A,K WHERE
; A IS A BASE ADDRESS (OF A VARIABLE OR ARRAY) AND K IS A TWO-BYTE
; INTEGER WORD SPECIFYING AT WHICH BYTE OF A THE STRING BEGINS.  K MAY BE
; POSITIVE, ZERO, OR NEGATIVE.  K=1 MEANS THE FIRST BYTE OF A.
;  
; CALL FILL(A1,K1,A2,K2,L)
;  
;      THIS ROUTINE STORES THE BYTE AT A1,K1 INTO EVERY BYTE OF THE STRING
; OF LENGTH L BEGINNING AT A2,K2.
;  
;	A1,K1 - SPECIFIES THE BYTE TO STORE.  A1 MAY BE A LITERAL
;		CONSTANT.
;	A2,K2 - SPECIFIES THE BEGINNING OF THE DESTINATION STRING.
;	L - A TWO-BYTE INTEGER COUNT OF THE NUMBER OF BYTES TO STORE.
;		IF L IS ZERO OR NEGATIVE, NO BYTES ARE STORED.
;  
;      THIS ROUTINE DOES NOTHING IF PASSED THE WRONG NUMBER OF ARGUMENTS.