diff --git a/source/Memory.h b/source/Memory.h
index 59156ba0..e26047c8 100644
--- a/source/Memory.h
+++ b/source/Memory.h
@@ -1,5 +1,17 @@
 #pragma once
 
+enum
+{
+	// Note: Alll are in bytes!
+	APPLE_SLOT_SIZE          = 0x0100, // 1 page  = $Cx00 .. $CxFF (slot 1 .. 7)
+	APPLE_SLOT_BEGIN         = 0xC100, // each slot has 1 page reserved for it
+	APPLE_SLOT_END           = 0xC7FF, //
+
+	FIRMWARE_EXPANSION_SIZE  = 0x0800, // 8 pages = $C800 .. $CFFF
+	FIRMWARE_EXPANSION_BEGIN = 0xC800, // [C800,CFFF)
+	FIRMWARE_EXPANSION_END   = 0xCFFF //
+};
+
 enum MemoryInitPattern_e
 {
 	  MIP_ZERO