diff --git a/source/core/gamecontrol.h b/source/core/gamecontrol.h
index b6458b232..5748649c5 100644
--- a/source/core/gamecontrol.h
+++ b/source/core/gamecontrol.h
@@ -56,7 +56,13 @@ void CONFIG_ReadCombatMacros();
 
 int GameMain();
 int GetAutomapZoom(int gZoom);
-inline void DrawOverheadMap(int x, int y, int ang) {} // transitional helper inline.
+
+// transitional helper inlines to define the interface before rewriting the code.
+inline void ClearAutomap() {}
+inline void MarkSectorSeen(int sect) {}
+inline void DrawOverheadMap(int x, int y, int ang) {} 
+
+
 void DrawCrosshair(int deftile, int health, double xdelta, double scale, PalEntry color = 0xffffffff);
 void updatePauseStatus();
 void DeferedStartGame(MapRecord* map, int skill);
diff --git a/source/exhumed/src/cheats.cpp b/source/exhumed/src/cheats.cpp
index a5cdfb495..06cb41dda 100644
--- a/source/exhumed/src/cheats.cpp
+++ b/source/exhumed/src/cheats.cpp
@@ -136,8 +136,8 @@ static bool SnakeCheat(cheatseq_t* c)
 static bool SphereCheat(cheatseq_t* c)
 {
 	Printf(PRINT_NOTIFY, "%s\n", GStrings("TXT_EX_FULLMAP"));
-	GrabMap();
-	bShowTowers = true;
+	gFullMap = !gFullMap; // only set the cheat flag so it can be toggled.
+	bShowTowers = gFullMap;
 	return true;
 }
 
diff --git a/source/exhumed/src/engine.h b/source/exhumed/src/engine.h
index 57c184641..54a2c64b5 100644
--- a/source/exhumed/src/engine.h
+++ b/source/exhumed/src/engine.h
@@ -105,9 +105,7 @@ extern short nPalDiff;
 // map
 
 extern short bShowTowers;
-extern int ldMapZoom;
 
-void InitMap();
 void GrabMap();
 void UpdateMap();
 void DrawMap();
diff --git a/source/exhumed/src/init.cpp b/source/exhumed/src/init.cpp
index 7a09fe99e..5912407bf 100644
--- a/source/exhumed/src/init.cpp
+++ b/source/exhumed/src/init.cpp
@@ -102,7 +102,7 @@ uint8_t LoadLevel(int nMap)
         InitSnakes();
         InitFishes();
         InitLights();
-        InitMap();
+        ClearAutomap();
         InitBubbles();
         InitObjects();
         InitLava();
diff --git a/source/exhumed/src/map.cpp b/source/exhumed/src/map.cpp
index a81764f17..3594b4c68 100644
--- a/source/exhumed/src/map.cpp
+++ b/source/exhumed/src/map.cpp
@@ -27,19 +27,6 @@ BEGIN_PS_NS
 
 
 short bShowTowers = false;
-int ldMapZoom;
-
-void MarkSectorSeen(short nSector);
-
-
-void InitMap()
-{
-    show2dsector.Zero();
-    memset(show2dwall,   0, sizeof(show2dwall));
-    memset(show2dsprite, 0, sizeof(show2dsprite));
-
-    ldMapZoom = 64;
-}
 
 void GrabMap()
 {
@@ -48,24 +35,6 @@ void GrabMap()
     }
 }
 
-void MarkSectorSeen(short nSector)
-{
-    if (!show2dsector[nSector])
-    {
-        show2dsector.Set(nSector);
-
-        short startwall = sector[nSector].wallptr;
-        short nWalls = sector[nSector].wallnum;
-        short endwall = startwall + nWalls;
-
-        while (startwall <= endwall)
-        {
-            show2dwall[startwall >> 3] = (1 << (startwall & 7)) | show2dwall[startwall >> 3];
-            startwall++;
-        }
-    }
-}
-
 
 void UpdateMap()
 {
diff --git a/source/games/duke/src/game_misc.cpp b/source/games/duke/src/game_misc.cpp
index 21720d285..ddd5b4f44 100644
--- a/source/games/duke/src/game_misc.cpp
+++ b/source/games/duke/src/game_misc.cpp
@@ -220,11 +220,9 @@ void V_AddBlend (float r, float g, float b, float a, float v_blend[4])
 
 void drawoverlays(double smoothratio)
 {
-	int i, j;
 	unsigned char fader = 0, fadeg = 0, fadeb = 0, fadef = 0, tintr = 0, tintg = 0, tintb = 0, tintf = 0, dotint = 0;
 
 	struct player_struct* pp;
-	walltype* wal;
 	int cposx, cposy, cang;
 
 	pp = &ps[screenpeek];
@@ -247,20 +245,7 @@ void drawoverlays(double smoothratio)
 	else
 		videoclearFade();
 
-	i = pp->cursectnum;
-
-	if (i >= 0) show2dsector.Set(i);
-	wal = &wall[sector[i].wallptr];
-	for (j = sector[i].wallnum; j > 0; j--, wal++)
-	{
-		i = wal->nextsector;
-		if (i < 0) continue;
-		if (wal->cstat & 0x0071) continue;
-		if (wall[wal->nextwall].cstat & 0x0071) continue;
-		if (sector[i].lotag == 32767) continue;
-		if (sector[i].ceilingz >= sector[i].floorz) continue;
-		show2dsector.Set(i);
-	}
+	MarkSectorSeen(pp->cursectnum);
 
 	if (ud.camerasprite == -1)
 	{
diff --git a/source/games/duke/src/premap.cpp b/source/games/duke/src/premap.cpp
index 740321101..a54d49ddf 100644
--- a/source/games/duke/src/premap.cpp
+++ b/source/games/duke/src/premap.cpp
@@ -688,10 +688,6 @@ void prelevel_common(int g)
     // RRRA E2L1 fog handling.
     fogactive = 0;
 
-    show2dsector.Zero();
-    memset(show2dwall, 0, sizeof(show2dwall));
-    memset(show2dsprite, 0, sizeof(show2dsprite));
-
     resetprestat(0, g);
     numclouds = 0;