diff --git a/sim/compile.lua b/sim/compile.lua
new file mode 100644
index 0000000..3ecdd0d
--- /dev/null
+++ b/sim/compile.lua
@@ -0,0 +1,12 @@
+
+function Simulation.compile(sim)
+	
+end
+
+function Simulation.decompile(sim)
+	
+end
+
+function Simulation.tickcompiled(sim)
+	
+end
diff --git a/sim/gate.lua b/sim/gate.lua
index 047315b..2addafc 100644
--- a/sim/gate.lua
+++ b/sim/gate.lua
@@ -1,11 +1,12 @@
 
 Gate = {}
 
-function Gate.new(self, objref, definition)
+function Gate.new(self, objref, definition, sim)
 	local o = {
 		objref = objref,
 		definition = definition,
-		ports = {}
+		ports = {},
+		sim = sim,
 	}
 	setmetatable(o, self)
 	self.__index = self
@@ -41,34 +42,14 @@ function Gate:getportisfalling(index)
 	return Port.isfalling(self.ports[index])
 end
 
--- function Gate:cb(...)
--- 	local args = {...}
--- 	local str = tostring(#args)
-
--- 	for i, v in ipairs(args) do
--- 		v = bool_to_int[v] or tostring(v)
--- 		str = str .. "\t" .. tostring(v)
--- 	end
-
--- 	sim:queuecallback(self, str)
--- end
-
-function Gate.cb(self, ...)
-	Simulation.queuecallback(sim, self, ...)
+function Gate.cb(gate, ...)
+	Simulation.queuecallback(gate.sim, gate, ...)
 end
 
 function Gate.queue(self, delay)
-	Simulation.queuegatelater(sim, self, delay)
+	Simulation.queuegatelater(self.sim, self, delay)
 end
 
-function Gate.testlogic(self, n)
-	--local time = os.clock()
-	--for i = 1, n do
-	--	self.definition.logic(self)
-	--end
-	--client:send("TEST\t" .. (os.clock()-time) .. "\n")
-end
-
-function Gate.gettick(self)
-	return sim.currenttick
+function Gate.gettick(gate)
+	return gate.sim.currenttick
 end
diff --git a/sim/gatedef.lua b/sim/gatedef.lua
index a61feaf..c6d9ee4 100644
--- a/sim/gatedef.lua
+++ b/sim/gatedef.lua
@@ -58,8 +58,8 @@ function GateDefinition.new(self, objref, name, description, init, logic, input,
 	return o
 end
 
-function GateDefinition.constructgate(self, objref, position, rotation)
-	local gate = Gate.new(Gate, objref, self)
+function GateDefinition.constructgate(self, objref, position, rotation, sim)
+	local gate = Gate.new(Gate, objref, self, sim)
 
 	for i = 1, #self.ports do
 		local portd = self.ports[i]
@@ -84,7 +84,7 @@ function GateDefinition.constructgate(self, objref, position, rotation)
 			pos[2] = x
 		end
 
-		Gate.addport(gate, Port.new(Port, type, dir, {position[1]+pos[1], position[2]+pos[2], position[3]+pos[3]}, portd.causeupdate))
+		Gate.addport(gate, Port.new(Port, type, dir, {position[1]+pos[1], position[2]+pos[2], position[3]+pos[3]}, portd.causeupdate, gate.sim))
 	end
 
 	return gate
diff --git a/sim/group.lua b/sim/group.lua
index b5d8ab9..2b4ae92 100644
--- a/sim/group.lua
+++ b/sim/group.lua
@@ -1,7 +1,7 @@
 
 Group = {}
 
-function Group.new(self)
+function Group.new(self, sim)
 	local o = {
 		state = false,
 		fxstate = false,
@@ -12,7 +12,9 @@ function Group.new(self)
 	
 		nwires = 0,
 		nout_ports = 0,
-		nin_ports = 0
+		nin_ports = 0,
+		
+		sim = sim,
 	}
 	setmetatable(o, self)
 	self.__index = self
@@ -33,7 +35,7 @@ function Group.addwire(self, wire)
 			
 			Wire.setgroup(wire, self)
 			Wire.update(wire)
-			Simulation.queuegroup(sim, self)
+			Simulation.queuegroup(self.sim, self)
 		end
 	end
 end
@@ -55,15 +57,15 @@ function Group.removewire(self, wire)
 	end
 
 	for k, wire in pairs(self.wires) do
-		Simulation.connectwire(sim, wire)
+		Simulation.connectwire(self.sim, wire)
 	end
 
 	for k, port in pairs(self.out_ports) do
-		Simulation.connectport(sim, port)
+		Simulation.connectport(self.sim, port)
 	end
 
 	for k, port in pairs(self.in_ports) do
-		Simulation.connectport(sim, port)
+		Simulation.connectport(self.sim, port)
 	end
 
 	self.wires = {}
@@ -81,7 +83,7 @@ function Group.addport(self, port)
 	if port.type == PortTypes.output then
 		self.out_ports[port] = port
 		self.nout_ports = self.nout_ports + 1
-		sim:queuegroup(self)
+		self.sim:queuegroup(self)
 	elseif port.type == PortTypes.input then
 		self.in_ports[port] = port
 		self.nin_ports = self.nin_ports + 1
@@ -98,7 +100,7 @@ function Group.removeport(self, port)
 		self.nin_ports = self.nin_ports - 1
 	end
 
-	Simulation.queuegroup(sim, self)
+	Simulation.queuegroup(self.sim, self)
 end
 
 function Group.mergewith(self, group)
@@ -137,12 +139,12 @@ end
 function Group.setstate(self, state)
 	if state ~= self.state then
 		self.state = state
-		self.updatetick = sim.currenttick
+		self.updatetick = self.sim.currenttick
 		
 		for k, port in pairs(self.in_ports) do
 			Port.setinputstate(port, state)
 		end
 		
-		Simulation.queuegroupfx(sim, self)
+		Simulation.queuegroupfx(self.sim, self)
 	end
 end
diff --git a/sim/main.lua b/sim/main.lua
index a1b61c3..05d40ab 100644
--- a/sim/main.lua
+++ b/sim/main.lua
@@ -1,4 +1,9 @@
 
+assert(getmetatable(_G)==nil, "_G already has a metatable")
+setmetatable(_G, {
+	__index = function(t, i) error("attempt to access nil variable "..i, 2) end
+})
+
 OPT_SAVE_DIR = arg[1] or error("must specify save location")
 OPT_SAVE_DIR = OPT_SAVE_DIR:gsub("\\", "/")
 OPT_SAVE_DIR = OPT_SAVE_DIR:gsub("/$", "")
@@ -16,6 +21,7 @@ dofile("gatedef.lua")
 dofile("gate.lua")
 dofile("port.lua")
 dofile("save.lua")
+dofile("compile.lua")
 
 OPT_TICK_ENABLED = true
 OPT_TICK_TIME = 0.032
@@ -39,7 +45,7 @@ local lastfxtime = 0
 local avgticks = {}
 local totalticks = 0
 
-sim = Simulation:new()
+local sim = Simulation:new()
 
 local units = {
 	"uHz",
@@ -151,7 +157,7 @@ while 1 do
 				
 				local position = vectotable(data[i+3])
 				local rotation = tonumber(data[i+4])
-				local gate = GateDefinition.constructgate(definition, objref, position, rotation)
+				local gate = GateDefinition.constructgate(definition, objref, position, rotation, sim)
 				
 				Simulation.addgate(sim, gate)
 				--print(gate.objref)
@@ -279,10 +285,6 @@ while 1 do
 			elseif data[i] == "TICK" then
 				Simulation.tick(sim)
 				ticks = ticks + 1
-			elseif data[i] == "TEST" then
-				local gate = Simulation.getgatebyref(sim, tonumber(data[i+1]))
-				Gate.testlogic(gate, tonumber(data[i+2]))
-				i = i + 2
 			elseif data[i] == "IN" then
 				local gate = Simulation.getgatebyref(sim, tonumber(data[i+1]))
 				local argc = tonumber(data[i+2])
diff --git a/sim/port.lua b/sim/port.lua
index 4280ef6..94dc694 100644
--- a/sim/port.lua
+++ b/sim/port.lua
@@ -17,7 +17,7 @@ Port = {
 	logictype = 1,
 }
 
-function Port.new(self, type, direction, position, causeupdate)
+function Port.new(self, type, direction, position, causeupdate, sim)
 	local o = {
 		type = type,
 		direction = direction,
@@ -26,6 +26,7 @@ function Port.new(self, type, direction, position, causeupdate)
 		state = false,
 		gate = nil,
 		group = nil,
+		sim = sim,
 	}
 	setmetatable(o, self)
 	self.__index = self
@@ -35,7 +36,7 @@ end
 function Port.setstate(port, state)
 	if state ~= port.state then
 		port.state = state
-		Simulation.queuegroup(sim, port.group)
+		Simulation.queuegroup(port.sim, port.group)
 	end
 end
 
@@ -43,7 +44,7 @@ function Port.setinputstate(port, state)
 	if state ~= port.state then
 		port.state = state
 		if port.causeupdate then
-			Simulation.queuegate(sim, port.gate)
+			Simulation.queuegate(port.sim, port.gate)
 		end
 	end
 end
@@ -57,14 +58,14 @@ function Port.isrising(self)
 	if self.group == nil then
 		return false
 	end
-	return self.group.state and (self.group.updatetick == sim.currenttick)
+	return self.group.state and (self.group.updatetick == self.sim.currenttick)
 end
 
 function Port.isfalling(self)
 	if self.group == nil then
 		return false
 	end
-	return self.group.state == false and (self.group.updatetick == sim.currenttick)
+	return self.group.state == false and (self.group.updatetick == self.sim.currenttick)
 end
 
 function Port.setgate(self, gate)
diff --git a/sim/simulation.lua b/sim/simulation.lua
index c8c18d3..3093498 100644
--- a/sim/simulation.lua
+++ b/sim/simulation.lua
@@ -207,7 +207,7 @@ function Simulation.connectwire(self, wire)
 	end
 	
 	if Wire.getgroup(wire)==nil then
-		Group.addwire(Group.new(Group), wire)
+		Group.addwire(Group.new(Group, self), wire)
 	end
 end
 
@@ -221,7 +221,7 @@ function Simulation.connectport(self, port)
 	end
 
 	if Port.getgroup(port) == nil then
-		Group.addport(Group.new(Group), port)
+		Group.addport(Group.new(Group, self), port)
 	end
 end
 
diff --git a/sim/wire.lua b/sim/wire.lua
index 1fa409b..7e032ce 100644
--- a/sim/wire.lua
+++ b/sim/wire.lua
@@ -20,7 +20,7 @@ function Wire.setlayer(self, layer)
 		Group.removewire(self.group, self)
 	end
 	self.layer = layer
-	Simulation.connectwire(sim, self)
+	Simulation.connectwire(self.sim, self)
 end
 
 function Wire.update(self)