add files for BASIC interpretor main loop and message printing

c64/basic/ab1e.print_string.s

@@ -0,0 +1,36 @@
+	;; Print string at $YYAA
+	;; Compute's Mapping the 64 p101
+
+print_string:
+	;; Setup pointer	
+	sty temp_string_ptr+1
+	sta temp_string_ptr+0
+
+	txa			
+	pha
+
+	;; Get offset ready
+	ldy #$00
+
+print_string_loop:	
+	;; Save Y in X, since X is preserved by chrout, but Y is not
+	tya
+	tax
+
+	lda (temp_string_ptr),y
+	beq print_string_end
+
+	jsr $FFD2 		; KERNAL CHROUT
+
+	txa
+	tay
+
+	iny
+	bne print_string_loop
+
+
+print_string_end:
+
+	pla
+	tax
+	rts