documentation update, added STATUS.md document

c64/kernal/memtop.s

@@ -1,14 +1,23 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; 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:
-	; p288 C64 Programmer's reference guide
-	; but for now we only support reading it
-	;;  http://unusedino.de/ec64/technical/project64/mapping_c64.html
+
 	bcc memtop_set
 	
-	LDY MEMSIZ+1
-	LDX MEMSIZ+0
+	ldy MEMSIZ+1
+	ldx MEMSIZ+0
 	rts
+
 memtop_set:
+
 	sty MEMSIZ+1
 	stx MEMSIZ+0