various I/O updates

2019-10-31 17:16:32 +01:00
1 parent bdcebb554f
commit c03c7abf45
@@ -0,0 +1,28 @@
+
+//
+// Sets .X to number of open RS-232 channels
+// Sets Carry if more than one is open
+
+
+#if HAS_RS232
+
+
+rs232_count_channels:
+
+	ldx #$00
+	ldy LDTND
+!:
+	dey
+	bmi close_rs232_search_done
+	lda FAT, y
+	cmp #$02
+	bne !-
+	inx
+	bpl !- // branch always
+	
+	cpx #$02
+	
+	rts
+
+
+#endif