further IO stack refactoring

c64/kernal/memory/fe25.memtop.s

@@ -0,0 +1,25 @@
+
+//
+// Official Kernal routine, described in:
+//
+// - [RG64] C64 Programmer's Reference Guide   - page 288
+// - [CM64] Compute's Mapping the Commodore 64 - page 240
+//
+// CPU registers that has to be preserved (see [RG64]): .A
+//
+
+MEMTOP:
+
+	bcc memtop_set
+	
+	ldy MEMSIZK+1
+	ldx MEMSIZK+0
+
+	// FALLTROUGH
+
+memtop_set: // for compatibility reasons this has to start at $FE2D
+
+	sty MEMSIZK+1
+	stx MEMSIZK+0
+	
+	rts