diff --git a/sim/compile.lua b/sim/compile.lua
index 7701c5a..3d08ce5 100644
--- a/sim/compile.lua
+++ b/sim/compile.lua
@@ -9,15 +9,15 @@ ffi.cdef([[
 ]])
 
 function Simulation.compile(sim)
-	-- assemble a list of all groups
-	local groups = {}
+	-- assemble a list of all nets
+	local all_nets = {}
 	for wire_idx, wire in pairs(sim.wires) do
-		local group = Wire.getgroup(wire)
-		groups[group] = group
+		local net = Wire.getgroup(wire)
+		all_nets[net] = net
 	end
-	local num_groups = 0
-	for group_id, group in pairs(groups) do
-		num_groups = num_groups+1
+	local num_nets = 0
+	for net_id, net in pairs(all_nets) do
+		num_nets = num_nets+1
 	end
 	
 	-- construct each gate into an array
diff --git a/sim/gate.lua b/sim/gate.lua
index 2addafc..3861d9c 100644
--- a/sim/gate.lua
+++ b/sim/gate.lua
@@ -38,18 +38,22 @@ function Gate.getportisrising(self, index)
 	return Port.isrising(self.ports[index])
 end
 
-function Gate:getportisfalling(index)
+function Gate.getportisfalling(self, index)
 	return Port.isfalling(self.ports[index])
 end
 
 function Gate.cb(gate, ...)
-	Simulation.queuecallback(gate.sim, gate, ...)
+	Simulation.queuecallback(Gate.getsim(gate), gate, ...)
 end
 
-function Gate.queue(self, delay)
-	Simulation.queuegatelater(self.sim, self, delay)
+function Gate.queue(gate, delay)
+	Simulation.queuegatelater(Gate.getsim(gate), gate, delay)
 end
 
 function Gate.gettick(gate)
-	return gate.sim.currenttick
+	return Gate.getsim(gate).currenttick
+end
+
+function Gate.getsim(gate)
+	return gate.sim
 end
diff --git a/sim/gatedef.lua b/sim/gatedef.lua
index c6d9ee4..631ceaf 100644
--- a/sim/gatedef.lua
+++ b/sim/gatedef.lua
@@ -84,7 +84,7 @@ function GateDefinition.constructgate(self, objref, position, rotation, sim)
 			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.sim))
+		Gate.addport(gate, Port.new(Port, type, dir, {position[1]+pos[1], position[2]+pos[2], position[3]+pos[3]}, portd.causeupdate, Gate.getsim(gate)))
 	end
 
 	return gate
diff --git a/sim/group.lua b/sim/group.lua
index 2b4ae92..7aaec39 100644
--- a/sim/group.lua
+++ b/sim/group.lua
@@ -35,7 +35,7 @@ function Group.addwire(self, wire)
 			
 			Wire.setgroup(wire, self)
 			Wire.update(wire)
-			Simulation.queuegroup(self.sim, self)
+			Simulation.queuegroup(Group.getsim(self), self)
 		end
 	end
 end
@@ -43,35 +43,37 @@ end
 function Group.removewire(self, wire)
 	Wire.setgroup(wire, nil)
 	self.wires[wire] = nil
-
+	
+	local sim = Group.getsim(self)
+	
 	for k, wire in pairs(self.wires) do
 		Wire.setgroup(wire, nil)
 	end
-
+	
 	for k, port in pairs(self.out_ports) do
 		Port.setgroup(port, nil)
 	end
-
+	
 	for k, port in pairs(self.in_ports) do
 		Port.setgroup(port, nil)
 	end
-
+	
 	for k, wire in pairs(self.wires) do
-		Simulation.connectwire(self.sim, wire)
+		Simulation.connectwire(sim. wire)
 	end
-
+	
 	for k, port in pairs(self.out_ports) do
-		Simulation.connectport(self.sim, port)
+		Simulation.connectport(sim, port)
 	end
-
+	
 	for k, port in pairs(self.in_ports) do
-		Simulation.connectport(self.sim, port)
+		Simulation.connectport(sim, port)
 	end
-
+	
 	self.wires = {}
 	self.out_ports = {}
 	self.in_ports = {}
-
+	
 	self.nwires = 0
 	self.nout_ports = 0
 	self.nin_ports = 0
@@ -83,7 +85,7 @@ function Group.addport(self, port)
 	if port.type == PortTypes.output then
 		self.out_ports[port] = port
 		self.nout_ports = self.nout_ports + 1
-		self.sim:queuegroup(self)
+		Simulation.queuegroup(Group.getsim(self), self)
 	elseif port.type == PortTypes.input then
 		self.in_ports[port] = port
 		self.nin_ports = self.nin_ports + 1
@@ -100,11 +102,11 @@ function Group.removeport(self, port)
 		self.nin_ports = self.nin_ports - 1
 	end
 
-	Simulation.queuegroup(self.sim, self)
+	Simulation.queuegroup(Group.getsim(self), self)
 end
 
 function Group.mergewith(self, group)
-	if self:getsize() >= group:getsize() then
+	if Group.getsize(self) >= Group.getsize(group) then
 		Group.mergeinto(group, self)
 		return self
 	else
@@ -139,12 +141,16 @@ end
 function Group.setstate(self, state)
 	if state ~= self.state then
 		self.state = state
-		self.updatetick = self.sim.currenttick
+		self.updatetick = Group.getsim(self).currenttick
 		
 		for k, port in pairs(self.in_ports) do
 			Port.setinputstate(port, state)
 		end
 		
-		Simulation.queuegroupfx(self.sim, self)
+		Simulation.queuegroupfx(Group.getsim(self), self)
 	end
 end
+
+function Group.getsim(group)
+	return group.sim
+end
diff --git a/sim/main.lua b/sim/main.lua
index 618886e..65f2b3f 100644
--- a/sim/main.lua
+++ b/sim/main.lua
@@ -48,7 +48,7 @@ local lastfxtime = 0
 local avgticks = {}
 local totalticks = 0
 
-local sim = Simulation:new()
+local sim = Simulation.new(Simulation)
 
 local units = {
 	"uHz",
@@ -322,12 +322,12 @@ while 1 do
 			
 			if OPT_TICK_TIME==0 then
 				for i = 1, OPT_TICK_INF do
-					sim:tick()
+					Simulation.tick(sim)
 				end
 				ticks = ticks+OPT_TICK_INF
 			else
 				for i = 1, OPT_TICK_MULT do
-					sim:tick()
+					Simulation.tick(sim)
 					ticks = ticks+1
 					
 					local elapsed = os.clock()-time
diff --git a/sim/port.lua b/sim/port.lua
index 94dc694..bb3a23c 100644
--- a/sim/port.lua
+++ b/sim/port.lua
@@ -36,7 +36,7 @@ end
 function Port.setstate(port, state)
 	if state ~= port.state then
 		port.state = state
-		Simulation.queuegroup(port.sim, port.group)
+		Simulation.queuegroup(Port.getsim(port), port.group)
 	end
 end
 
@@ -44,46 +44,50 @@ function Port.setinputstate(port, state)
 	if state ~= port.state then
 		port.state = state
 		if port.causeupdate then
-			Simulation.queuegate(port.sim, port.gate)
+			Simulation.queuegate(Port.getsim(port), port.gate)
 		end
 	end
 end
 
-function Port.getconnectionposition(self)
-	local offset = PortDirections[self.direction]
-	return {self.position[1]+offset[1], self.position[2]+offset[2], self.position[3]+offset[3]}
+function Port.getconnectionposition(port)
+	local offset = PortDirections[port.direction]
+	return {port.position[1]+offset[1], port.position[2]+offset[2], port.position[3]+offset[3]}
 end
 
-function Port.isrising(self)
-	if self.group == nil then
+function Port.isrising(port)
+	if port.group == nil then
 		return false
 	end
-	return self.group.state and (self.group.updatetick == self.sim.currenttick)
+	return port.group.state and (port.group.updatetick == Port.getsim(port).currenttick)
 end
 
-function Port.isfalling(self)
-	if self.group == nil then
+function Port.isfalling(port)
+	if port.group == nil then
 		return false
 	end
-	return self.group.state == false and (self.group.updatetick == self.sim.currenttick)
+	return port.group.state == false and (port.updatetick == Port.getsim(port).currenttick)
 end
 
-function Port.setgate(self, gate)
-	self.gate = gate
+function Port.setgate(port, gate)
+	port.gate = gate
 end
 
-function Port.setgroup(self, group)
-	self.group = group
+function Port.setgroup(port, group)
+	port.group = group
 end
 
-function Port.getgroup(self)
-	return self.group
+function Port.getgroup(port)
+	return port.group
 end
 
-function Port.gettype(self)
-	return self.type
+function Port.gettype(port)
+	return port.type
 end
 
-function Port.getstate(self)
-	return self.state
+function Port.getstate(port)
+	return port.state
+end
+
+function Port.getsim(port)
+	return port.sim
 end
diff --git a/sim/simulation.lua b/sim/simulation.lua
index 525ee00..ded32af 100644
--- a/sim/simulation.lua
+++ b/sim/simulation.lua
@@ -213,7 +213,7 @@ end
 
 function Simulation.connectport(self, port)
 	local connpos = Port.getconnectionposition(port)
-	local objs = self:getfromworld(connpos[1], connpos[2], connpos[3])
+	local objs = Simulation.getfromworld(self, connpos[1], connpos[2], connpos[3])
 	for k, obj in pairs(objs) do
 		if obj ~= port and obj.group ~= nil then
 			Group.addport(obj.group, port)
diff --git a/sim/wire.lua b/sim/wire.lua
index 7ef72d5..25c9713 100644
--- a/sim/wire.lua
+++ b/sim/wire.lua
@@ -21,7 +21,7 @@ function Wire.setlayer(self, layer)
 		Group.removewire(self.group, self)
 	end
 	self.layer = layer
-	Simulation.connectwire(self.sim, self)
+	Simulation.connectwire(Wire.getsim(self), self)
 end
 
 function Wire.update(self)
@@ -47,3 +47,7 @@ end
 function Wire.getbounds(self)
 	return self.bounds
 end
+
+function Wire.getsim(wire)
+	return wire.sim
+end