diff --git a/README.md b/README.md
index 3553a5e35..0f0a33edb 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Ethereum
 Ethereum Go Development package (C) Jeffrey Wilcke
 
 Ethereum is currently in its testing phase. The current state is "Proof
-of Concept 3". For build instructions see the [Wiki](https://github.com/ethereum/go-ethereum/wiki/Building-Ethereum(Go)).
+of Concept 3.5". For build instructions see the [Wiki](https://github.com/ethereum/go-ethereum/wiki/Building-Ethereum(Go)).
 
 Ethereum Go is split up in several sub packages Please refer to each
 individual package for more information.
diff --git a/ethchain/address.go b/ethchain/address.go
index aa1709f2c..0b3ef7c05 100644
--- a/ethchain/address.go
+++ b/ethchain/address.go
@@ -6,23 +6,39 @@ import (
 )
 
 type Account struct {
-	Amount *big.Int
-	Nonce  uint64
+	address []byte
+	Amount  *big.Int
+	Nonce   uint64
 }
 
-func NewAccount(amount *big.Int) *Account {
-	return &Account{Amount: amount, Nonce: 0}
+func NewAccount(address []byte, amount *big.Int) *Account {
+	return &Account{address, amount, 0}
 }
 
-func NewAccountFromData(data []byte) *Account {
-	address := &Account{}
-	address.RlpDecode(data)
+func NewAccountFromData(address, data []byte) *Account {
+	account := &Account{address: address}
+	account.RlpDecode(data)
 
-	return address
+	return account
 }
 
 func (a *Account) AddFee(fee *big.Int) {
-	a.Amount.Add(a.Amount, fee)
+	a.AddFunds(fee)
+}
+
+func (a *Account) AddFunds(funds *big.Int) {
+	a.Amount.Add(a.Amount, funds)
+}
+
+func (a *Account) Address() []byte {
+	return a.address
+}
+
+// Implements Callee
+func (a *Account) ReturnGas(value *big.Int, state *State) {
+	// Return the value back to the sender
+	a.AddFunds(value)
+	state.UpdateAccount(a.address, a)
 }
 
 func (a *Account) RlpEncode() []byte {
diff --git a/ethchain/block.go b/ethchain/block.go
index d42aa7d83..732739c1b 100644
--- a/ethchain/block.go
+++ b/ethchain/block.go
@@ -142,7 +142,7 @@ func (block *Block) PayFee(addr []byte, fee *big.Int) bool {
 	data := block.state.trie.Get(string(block.Coinbase))
 
 	// Get the ether (Coinbase) and add the fee (gief fee to miner)
-	ether := NewAccountFromData([]byte(data))
+	ether := NewAccountFromData(block.Coinbase, []byte(data))
 
 	base = new(big.Int)
 	ether.Amount = base.Add(ether.Amount, fee)
diff --git a/ethchain/block_manager_test.go b/ethchain/block_manager_test.go
index ec4fbe8c5..3a1e5f510 100644
--- a/ethchain/block_manager_test.go
+++ b/ethchain/block_manager_test.go
@@ -1,5 +1,6 @@
 package ethchain
 
+/*
 import (
 	_ "fmt"
 	"github.com/ethereum/eth-go/ethdb"
@@ -14,9 +15,10 @@ func TestVm(t *testing.T) {
 
 	db, _ := ethdb.NewMemDatabase()
 	ethutil.Config.Db = db
-	bm := NewBlockManager(nil)
+	bm := NewStateManager(nil)
 
 	block := bm.bc.genesisBlock
+	bm.Prepare(block.State(), block.State())
 	script := Compile([]string{
 		"PUSH",
 		"1",
@@ -31,3 +33,4 @@ func TestVm(t *testing.T) {
 	tx2.Sign([]byte("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"))
 	bm.ApplyTransactions(block, []*Transaction{tx2})
 }
+*/
diff --git a/ethchain/closure.go b/ethchain/closure.go
new file mode 100644
index 000000000..2e809aa9d
--- /dev/null
+++ b/ethchain/closure.go
@@ -0,0 +1,90 @@
+package ethchain
+
+// TODO Re write VM to use values instead of big integers?
+
+import (
+	"github.com/ethereum/eth-go/ethutil"
+	"math/big"
+)
+
+type Callee interface {
+	ReturnGas(*big.Int, *State)
+	Address() []byte
+}
+
+type ClosureBody interface {
+	Callee
+	ethutil.RlpEncodable
+	GetMem(*big.Int) *ethutil.Value
+	SetMem(*big.Int, *ethutil.Value)
+}
+
+// Basic inline closure object which implement the 'closure' interface
+type Closure struct {
+	callee Callee
+	object ClosureBody
+	State  *State
+
+	Gas   *big.Int
+	Value *big.Int
+
+	Args []byte
+}
+
+// Create a new closure for the given data items
+func NewClosure(callee Callee, object ClosureBody, state *State, gas, val *big.Int) *Closure {
+	return &Closure{callee, object, state, gas, val, nil}
+}
+
+// Retuns the x element in data slice
+func (c *Closure) GetMem(x *big.Int) *ethutil.Value {
+	m := c.object.GetMem(x)
+	if m == nil {
+		return ethutil.EmptyValue()
+	}
+
+	return m
+}
+
+func (c *Closure) SetMem(x *big.Int, val *ethutil.Value) {
+	c.object.SetMem(x, val)
+}
+
+func (c *Closure) Address() []byte {
+	return c.object.Address()
+}
+
+func (c *Closure) Call(vm *Vm, args []byte) []byte {
+	c.Args = args
+
+	return vm.RunClosure(c)
+}
+
+func (c *Closure) Return(ret []byte) []byte {
+	// Return the remaining gas to the callee
+	// If no callee is present return it to
+	// the origin (i.e. contract or tx)
+	if c.callee != nil {
+		c.callee.ReturnGas(c.Gas, c.State)
+	} else {
+		c.object.ReturnGas(c.Gas, c.State)
+		// TODO incase it's a POST contract we gotta serialise the contract again.
+		// But it's not yet defined
+	}
+
+	return ret
+}
+
+// Implement the Callee interface
+func (c *Closure) ReturnGas(gas *big.Int, state *State) {
+	// Return the gas to the closure
+	c.Gas.Add(c.Gas, gas)
+}
+
+func (c *Closure) Object() ClosureBody {
+	return c.object
+}
+
+func (c *Closure) Callee() Callee {
+	return c.callee
+}
diff --git a/ethchain/contract.go b/ethchain/contract.go
index 21ac828fe..f7ae01753 100644
--- a/ethchain/contract.go
+++ b/ethchain/contract.go
@@ -9,26 +9,22 @@ type Contract struct {
 	Amount *big.Int
 	Nonce  uint64
 	//state  *ethutil.Trie
-	state *State
+	state   *State
+	address []byte
 }
 
-func NewContract(Amount *big.Int, root []byte) *Contract {
-	contract := &Contract{Amount: Amount, Nonce: 0}
+func NewContract(address []byte, Amount *big.Int, root []byte) *Contract {
+	contract := &Contract{address: address, Amount: Amount, Nonce: 0}
 	contract.state = NewState(ethutil.NewTrie(ethutil.Config.Db, string(root)))
 
 	return contract
 }
 
-func (c *Contract) RlpEncode() []byte {
-	return ethutil.Encode([]interface{}{c.Amount, c.Nonce, c.state.trie.Root})
-}
+func NewContractFromBytes(address, data []byte) *Contract {
+	contract := &Contract{address: address}
+	contract.RlpDecode(data)
 
-func (c *Contract) RlpDecode(data []byte) {
-	decoder := ethutil.NewValueFromBytes(data)
-
-	c.Amount = decoder.Get(0).BigInt()
-	c.Nonce = decoder.Get(1).Uint()
-	c.state = NewState(ethutil.NewTrie(ethutil.Config.Db, decoder.Get(2).Interface()))
+	return contract
 }
 
 func (c *Contract) Addr(addr []byte) *ethutil.Value {
@@ -43,19 +39,45 @@ func (c *Contract) State() *State {
 	return c.state
 }
 
-func (c *Contract) GetMem(num int) *ethutil.Value {
-	nb := ethutil.BigToBytes(big.NewInt(int64(num)), 256)
+func (c *Contract) GetMem(num *big.Int) *ethutil.Value {
+	nb := ethutil.BigToBytes(num, 256)
 
 	return c.Addr(nb)
 }
 
+func (c *Contract) SetMem(num *big.Int, val *ethutil.Value) {
+	addr := ethutil.BigToBytes(num, 256)
+	c.state.trie.Update(string(addr), string(val.Encode()))
+}
+
+// Return the gas back to the origin. Used by the Virtual machine or Closures
+func (c *Contract) ReturnGas(val *big.Int, state *State) {
+	c.Amount.Add(c.Amount, val)
+}
+
+func (c *Contract) Address() []byte {
+	return c.address
+}
+
+func (c *Contract) RlpEncode() []byte {
+	return ethutil.Encode([]interface{}{c.Amount, c.Nonce, c.state.trie.Root})
+}
+
+func (c *Contract) RlpDecode(data []byte) {
+	decoder := ethutil.NewValueFromBytes(data)
+
+	c.Amount = decoder.Get(0).BigInt()
+	c.Nonce = decoder.Get(1).Uint()
+	c.state = NewState(ethutil.NewTrie(ethutil.Config.Db, decoder.Get(2).Interface()))
+}
+
 func MakeContract(tx *Transaction, state *State) *Contract {
 	// Create contract if there's no recipient
 	if tx.IsContract() {
 		addr := tx.Hash()[12:]
 
 		value := tx.Value
-		contract := NewContract(value, []byte(""))
+		contract := NewContract(addr, value, []byte(""))
 		state.trie.Update(string(addr), string(contract.RlpEncode()))
 		for i, val := range tx.Data {
 			if len(val) > 0 {
diff --git a/ethchain/stack.go b/ethchain/stack.go
index 13b0f247b..3c2899e62 100644
--- a/ethchain/stack.go
+++ b/ethchain/stack.go
@@ -2,6 +2,7 @@ package ethchain
 
 import (
 	"fmt"
+	_ "github.com/ethereum/eth-go/ethutil"
 	"math/big"
 )
 
@@ -9,111 +10,142 @@ type OpCode int
 
 // Op codes
 const (
-	oSTOP           = 0x00
-	oADD            = 0x01
-	oMUL            = 0x02
-	oSUB            = 0x03
-	oDIV            = 0x04
-	oSDIV           = 0x05
-	oMOD            = 0x06
-	oSMOD           = 0x07
-	oEXP            = 0x08
-	oNEG            = 0x09
-	oLT             = 0x0a
-	oLE             = 0x0b
-	oGT             = 0x0c
-	oGE             = 0x0d
-	oEQ             = 0x0e
-	oNOT            = 0x0f
-	oMYADDRESS      = 0x10
-	oTXSENDER       = 0x11
-	oTXVALUE        = 0x12
-	oTXDATAN        = 0x13
-	oTXDATA         = 0x14
-	oBLK_PREVHASH   = 0x15
-	oBLK_COINBASE   = 0x16
-	oBLK_TIMESTAMP  = 0x17
-	oBLK_NUMBER     = 0x18
-	oBLK_DIFFICULTY = 0x19
-	oBLK_NONCE      = 0x1a
-	oBASEFEE        = 0x1b
-	oSHA256         = 0x20
-	oRIPEMD160      = 0x21
-	oECMUL          = 0x22
-	oECADD          = 0x23
-	oECSIGN         = 0x24
-	oECRECOVER      = 0x25
-	oECVALID        = 0x26
-	oSHA3           = 0x27
-	oPUSH           = 0x30
-	oPOP            = 0x31
-	oDUP            = 0x32
-	oSWAP           = 0x33
-	oMLOAD          = 0x34
-	oMSTORE         = 0x35
-	oSLOAD          = 0x36
-	oSSTORE         = 0x37
-	oJMP            = 0x38
-	oJMPI           = 0x39
-	oIND            = 0x3a
-	oEXTRO          = 0x3b
-	oBALANCE        = 0x3c
-	oMKTX           = 0x3d
-	oSUICIDE        = 0x3f
+	// 0x0 range - arithmetic ops
+	oSTOP = 0x00
+	oADD  = 0x01
+	oMUL  = 0x02
+	oSUB  = 0x03
+	oDIV  = 0x04
+	oSDIV = 0x05
+	oMOD  = 0x06
+	oSMOD = 0x07
+	oEXP  = 0x08
+	oNEG  = 0x09
+	oLT   = 0x0a
+	oGT   = 0x0b
+	oEQ   = 0x0c
+	oNOT  = 0x0d
+
+	// 0x10 range - bit ops
+	oAND  = 0x10
+	oOR   = 0x11
+	oXOR  = 0x12
+	oBYTE = 0x13
+
+	// 0x20 range - crypto
+	oSHA3 = 0x20
+
+	// 0x30 range - closure state
+	oADDRESS      = 0x30
+	oBALANCE      = 0x31
+	oORIGIN       = 0x32
+	oCALLER       = 0x33
+	oCALLVALUE    = 0x34
+	oCALLDATA     = 0x35
+	oCALLDATASIZE = 0x36
+	oGASPRICE     = 0x37
+
+	// 0x40 range - block operations
+	oPREVHASH   = 0x40
+	oCOINBASE   = 0x41
+	oTIMESTAMP  = 0x42
+	oNUMBER     = 0x43
+	oDIFFICULTY = 0x44
+	oGASLIMIT   = 0x45
+
+	// 0x50 range - 'storage' and execution
+	oPUSH    = 0x50
+	oPOP     = 0x51
+	oDUP     = 0x52
+	oSWAP    = 0x53
+	oMLOAD   = 0x54
+	oMSTORE  = 0x55
+	oMSTORE8 = 0x56
+	oSLOAD   = 0x57
+	oSSTORE  = 0x58
+	oJUMP    = 0x59
+	oJUMPI   = 0x5a
+	oPC      = 0x5b
+	oMSIZE   = 0x5c
+
+	// 0x60 range - closures
+	oCREATE = 0x60
+	oCALL   = 0x61
+	oRETURN = 0x62
+
+	// 0x70 range - other
+	oLOG     = 0x70 // XXX Unofficial
+	oSUICIDE = 0x7f
 )
 
 // Since the opcodes aren't all in order we can't use a regular slice
 var opCodeToString = map[OpCode]string{
-	oSTOP:           "STOP",
-	oADD:            "ADD",
-	oMUL:            "MUL",
-	oSUB:            "SUB",
-	oDIV:            "DIV",
-	oSDIV:           "SDIV",
-	oMOD:            "MOD",
-	oSMOD:           "SMOD",
-	oEXP:            "EXP",
-	oNEG:            "NEG",
-	oLT:             "LT",
-	oLE:             "LE",
-	oGT:             "GT",
-	oGE:             "GE",
-	oEQ:             "EQ",
-	oNOT:            "NOT",
-	oMYADDRESS:      "MYADDRESS",
-	oTXSENDER:       "TXSENDER",
-	oTXVALUE:        "TXVALUE",
-	oTXDATAN:        "TXDATAN",
-	oTXDATA:         "TXDATA",
-	oBLK_PREVHASH:   "BLK_PREVHASH",
-	oBLK_COINBASE:   "BLK_COINBASE",
-	oBLK_TIMESTAMP:  "BLK_TIMESTAMP",
-	oBLK_NUMBER:     "BLK_NUMBER",
-	oBLK_DIFFICULTY: "BLK_DIFFICULTY",
-	oBASEFEE:        "BASEFEE",
-	oSHA256:         "SHA256",
-	oRIPEMD160:      "RIPEMD160",
-	oECMUL:          "ECMUL",
-	oECADD:          "ECADD",
-	oECSIGN:         "ECSIGN",
-	oECRECOVER:      "ECRECOVER",
-	oECVALID:        "ECVALID",
-	oSHA3:           "SHA3",
-	oPUSH:           "PUSH",
-	oPOP:            "POP",
-	oDUP:            "DUP",
-	oSWAP:           "SWAP",
-	oMLOAD:          "MLOAD",
-	oMSTORE:         "MSTORE",
-	oSLOAD:          "SLOAD",
-	oSSTORE:         "SSTORE",
-	oJMP:            "JMP",
-	oJMPI:           "JMPI",
-	oIND:            "IND",
-	oEXTRO:          "EXTRO",
-	oBALANCE:        "BALANCE",
-	oMKTX:           "MKTX",
-	oSUICIDE:        "SUICIDE",
+	// 0x0 range - arithmetic ops
+	oSTOP: "STOP",
+	oADD:  "ADD",
+	oMUL:  "MUL",
+	oSUB:  "SUB",
+	oDIV:  "DIV",
+	oSDIV: "SDIV",
+	oMOD:  "MOD",
+	oSMOD: "SMOD",
+	oEXP:  "EXP",
+	oNEG:  "NEG",
+	oLT:   "LT",
+	oGT:   "GT",
+	oEQ:   "EQ",
+	oNOT:  "NOT",
+
+	// 0x10 range - bit ops
+	oAND:  "AND",
+	oOR:   "OR",
+	oXOR:  "XOR",
+	oBYTE: "BYTE",
+
+	// 0x20 range - crypto
+	oSHA3: "SHA3",
+
+	// 0x30 range - closure state
+	oADDRESS:      "ADDRESS",
+	oBALANCE:      "BALANCE",
+	oORIGIN:       "ORIGIN",
+	oCALLER:       "CALLER",
+	oCALLVALUE:    "CALLVALUE",
+	oCALLDATA:     "CALLDATA",
+	oCALLDATASIZE: "CALLDATASIZE",
+	oGASPRICE:     "TXGASPRICE",
+
+	// 0x40 range - block operations
+	oPREVHASH:   "PREVHASH",
+	oCOINBASE:   "COINBASE",
+	oTIMESTAMP:  "TIMESTAMP",
+	oNUMBER:     "NUMBER",
+	oDIFFICULTY: "DIFFICULTY",
+	oGASLIMIT:   "GASLIMIT",
+
+	// 0x50 range - 'storage' and execution
+	oPUSH:    "PUSH",
+	oPOP:     "POP",
+	oDUP:     "DUP",
+	oSWAP:    "SWAP",
+	oMLOAD:   "MLOAD",
+	oMSTORE:  "MSTORE",
+	oMSTORE8: "MSTORE8",
+	oSLOAD:   "SLOAD",
+	oSSTORE:  "SSTORE",
+	oJUMP:    "JUMP",
+	oJUMPI:   "JUMPI",
+	oPC:      "PC",
+	oMSIZE:   "MSIZE",
+
+	// 0x60 range - closures
+	oCREATE: "CREATE",
+	oCALL:   "CALL",
+	oRETURN: "RETURN",
+
+	// 0x70 range - other
+	oLOG:     "LOG",
+	oSUICIDE: "SUICIDE",
 }
 
 func (o OpCode) String() string {
@@ -141,35 +173,27 @@ func NewStack() *Stack {
 }
 
 func (st *Stack) Pop() *big.Int {
-	s := len(st.data)
-
-	str := st.data[s-1]
-	st.data = st.data[:s-1]
+	str := st.data[0]
+	st.data = st.data[1:]
 
 	return str
 }
 
 func (st *Stack) Popn() (*big.Int, *big.Int) {
-	s := len(st.data)
-
-	ints := st.data[s-2:]
-	st.data = st.data[:s-2]
+	ints := st.data[:2]
+	st.data = st.data[2:]
 
 	return ints[0], ints[1]
 }
 
 func (st *Stack) Peek() *big.Int {
-	s := len(st.data)
-
-	str := st.data[s-1]
+	str := st.data[0]
 
 	return str
 }
 
 func (st *Stack) Peekn() (*big.Int, *big.Int) {
-	s := len(st.data)
-
-	ints := st.data[s-2:]
+	ints := st.data[:2]
 
 	return ints[0], ints[1]
 }
@@ -188,3 +212,45 @@ func (st *Stack) Print() {
 	}
 	fmt.Println("#############")
 }
+
+type Memory struct {
+	store []byte
+}
+
+func (m *Memory) Set(offset, size int64, value []byte) {
+	totSize := offset + size
+	lenSize := int64(len(m.store) - 1)
+	if totSize > lenSize {
+		// Calculate the diff between the sizes
+		diff := totSize - lenSize
+		if diff > 0 {
+			// Create a new empty slice and append it
+			newSlice := make([]byte, diff-1)
+			// Resize slice
+			m.store = append(m.store, newSlice...)
+		}
+	}
+	copy(m.store[offset:offset+size], value)
+}
+
+func (m *Memory) Get(offset, size int64) []byte {
+	return m.store[offset : offset+size]
+}
+
+func (m *Memory) Len() int {
+	return len(m.store)
+}
+
+func (m *Memory) Print() {
+	fmt.Println("### MEM ###")
+	if len(m.store) > 0 {
+		addr := 0
+		for i := 0; i+32 < len(m.store); i += 32 {
+			fmt.Printf("%03d %v\n", addr, m.store[i:i+32])
+			addr++
+		}
+	} else {
+		fmt.Println("-- empty --")
+	}
+	fmt.Println("###########")
+}
diff --git a/ethchain/state.go b/ethchain/state.go
index b9c2c576d..1860647f2 100644
--- a/ethchain/state.go
+++ b/ethchain/state.go
@@ -63,8 +63,7 @@ func (s *State) GetContract(addr []byte) *Contract {
 	}
 
 	// build contract
-	contract := &Contract{}
-	contract.RlpDecode([]byte(data))
+	contract := NewContractFromBytes(addr, []byte(data))
 
 	// Check if there's a cached state for this contract
 	cachedState := s.states[string(addr)]
@@ -78,27 +77,19 @@ func (s *State) GetContract(addr []byte) *Contract {
 	return contract
 }
 
-func (s *State) UpdateContract(addr []byte, contract *Contract) {
+func (s *State) UpdateContract(contract *Contract) {
+	addr := contract.Address()
+
+	s.states[string(addr)] = contract.state
 	s.trie.Update(string(addr), string(contract.RlpEncode()))
 }
 
-func Compile(code []string) (script []string) {
-	script = make([]string, len(code))
-	for i, val := range code {
-		instr, _ := ethutil.CompileInstr(val)
-
-		script[i] = string(instr)
-	}
-
-	return
-}
-
 func (s *State) GetAccount(addr []byte) (account *Account) {
 	data := s.trie.Get(string(addr))
 	if data == "" {
-		account = NewAccount(big.NewInt(0))
+		account = NewAccount(addr, big.NewInt(0))
 	} else {
-		account = NewAccountFromData([]byte(data))
+		account = NewAccountFromData(addr, []byte(data))
 	}
 
 	return
@@ -153,3 +144,35 @@ func (s *State) Get(key []byte) (*ethutil.Value, ObjType) {
 
 	return val, typ
 }
+
+func (s *State) Put(key, object []byte) {
+	s.trie.Update(string(key), string(object))
+}
+
+func (s *State) Root() interface{} {
+	return s.trie.Root
+}
+
+// Script compilation functions
+// Compiles strings to machine code
+func Compile(code []string) (script []string) {
+	script = make([]string, len(code))
+	for i, val := range code {
+		instr, _ := ethutil.CompileInstr(val)
+
+		script[i] = string(instr)
+	}
+
+	return
+}
+
+func CompileToValues(code []string) (script []*ethutil.Value) {
+	script = make([]*ethutil.Value, len(code))
+	for i, val := range code {
+		instr, _ := ethutil.CompileInstr(val)
+
+		script[i] = ethutil.NewValue(instr)
+	}
+
+	return
+}
diff --git a/ethchain/state_manager.go b/ethchain/state_manager.go
index 9118db211..5692a1d88 100644
--- a/ethchain/state_manager.go
+++ b/ethchain/state_manager.go
@@ -308,18 +308,17 @@ func (sm *StateManager) ProcessContract(contract *Contract, tx *Transaction, blo
 			}
 		}()
 	*/
-
-	vm := &Vm{}
-	//vm.Process(contract, block.state, RuntimeVars{
-	vm.Process(contract, sm.procState, RuntimeVars{
-		address:     tx.Hash()[12:],
+	caller := sm.procState.GetAccount(tx.Sender())
+	closure := NewClosure(caller, contract, sm.procState, tx.Gas, tx.Value)
+	vm := NewVm(sm.procState, RuntimeVars{
+		origin:      caller.Address(),
 		blockNumber: block.BlockInfo().Number,
-		sender:      tx.Sender(),
 		prevHash:    block.PrevHash,
 		coinbase:    block.Coinbase,
 		time:        block.Time,
 		diff:        block.Difficulty,
-		txValue:     tx.Value,
-		txData:      tx.Data,
+		// XXX Tx data? Could be just an argument to the closure instead
+		txData: nil,
 	})
+	closure.Call(vm, nil)
 }
diff --git a/ethchain/transaction.go b/ethchain/transaction.go
index 57df9cdc4..3b07c81d4 100644
--- a/ethchain/transaction.go
+++ b/ethchain/transaction.go
@@ -13,22 +13,31 @@ type Transaction struct {
 	Nonce     uint64
 	Recipient []byte
 	Value     *big.Int
+	Gas       *big.Int
+	Gasprice  *big.Int
 	Data      []string
-	Memory    []int
 	v         byte
 	r, s      []byte
 }
 
 func NewTransaction(to []byte, value *big.Int, data []string) *Transaction {
-	tx := Transaction{Recipient: to, Value: value}
-	tx.Nonce = 0
-
-	// Serialize the data
-	tx.Data = data
+	tx := Transaction{Recipient: to, Value: value, Nonce: 0, Data: data}
 
 	return &tx
 }
 
+func NewContractCreationTx(value, gasprice *big.Int, data []string) *Transaction {
+	return &Transaction{Value: value, Gasprice: gasprice, Data: data}
+}
+
+func NewContractMessageTx(to []byte, value, gasprice, gas *big.Int, data []string) *Transaction {
+	return &Transaction{Recipient: to, Value: value, Gasprice: gasprice, Gas: gas, Data: data}
+}
+
+func NewTx(to []byte, value *big.Int, data []string) *Transaction {
+	return &Transaction{Recipient: to, Value: value, Gasprice: big.NewInt(0), Gas: big.NewInt(0), Nonce: 0, Data: data}
+}
+
 // XXX Deprecated
 func NewTransactionFromData(data []byte) *Transaction {
 	return NewTransactionFromBytes(data)
diff --git a/ethchain/vm.go b/ethchain/vm.go
index 7e119ac99..126592b25 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -1,12 +1,12 @@
 package ethchain
 
 import (
-	"bytes"
-	"fmt"
+	_ "bytes"
+	_ "fmt"
 	"github.com/ethereum/eth-go/ethutil"
-	"github.com/obscuren/secp256k1-go"
+	_ "github.com/obscuren/secp256k1-go"
 	"log"
-	"math"
+	_ "math"
 	"math/big"
 )
 
@@ -18,122 +18,102 @@ type Vm struct {
 	mem map[string]*big.Int
 
 	vars RuntimeVars
+
+	state *State
 }
 
 type RuntimeVars struct {
-	address     []byte
+	origin      []byte
 	blockNumber uint64
-	sender      []byte
 	prevHash    []byte
 	coinbase    []byte
 	time        int64
 	diff        *big.Int
-	txValue     *big.Int
 	txData      []string
 }
 
-func (vm *Vm) Process(contract *Contract, state *State, vars RuntimeVars) {
-	vm.mem = make(map[string]*big.Int)
-	vm.stack = NewStack()
+func NewVm(state *State, vars RuntimeVars) *Vm {
+	return &Vm{vars: vars, state: state}
+}
 
-	addr := vars.address // tx.Hash()[12:]
-	// Instruction pointer
-	pc := 0
+var Pow256 = ethutil.BigPow(2, 256)
 
-	if contract == nil {
-		fmt.Println("Contract not found")
-		return
+func (vm *Vm) RunClosure(closure *Closure) []byte {
+	// If the amount of gas supplied is less equal to 0
+	if closure.Gas.Cmp(big.NewInt(0)) <= 0 {
+		// TODO Do something
 	}
 
-	Pow256 := ethutil.BigPow(2, 256)
+	// Memory for the current closure
+	mem := &Memory{}
+	// New stack (should this be shared?)
+	stack := NewStack()
+	// Instruction pointer
+	pc := big.NewInt(0)
+	// Current step count
+	step := 0
+	// The base for all big integer arithmetic
+	base := new(big.Int)
 
 	if ethutil.Config.Debug {
 		ethutil.Config.Log.Debugf("#   op\n")
 	}
 
-	stepcount := 0
-	totalFee := new(big.Int)
-
-out:
 	for {
-		stepcount++
-		// The base big int for all calculations. Use this for any results.
-		base := new(big.Int)
-		val := contract.GetMem(pc)
-		//fmt.Printf("%x = %d, %v %x\n", r, len(r), v, nb)
+		step++
+		// Get the memory location of pc
+		val := closure.GetMem(pc)
+		// Get the opcode (it must be an opcode!)
 		op := OpCode(val.Uint())
-
-		var fee *big.Int = new(big.Int)
-		var fee2 *big.Int = new(big.Int)
-		if stepcount > 16 {
-			fee.Add(fee, StepFee)
-		}
-
-		// Calculate the fees
-		switch op {
-		case oSSTORE:
-			y, x := vm.stack.Peekn()
-			val := contract.Addr(ethutil.BigToBytes(x, 256))
-			if val.IsEmpty() && len(y.Bytes()) > 0 {
-				fee2.Add(DataFee, StoreFee)
-			} else {
-				fee2.Sub(DataFee, StoreFee)
-			}
-		case oSLOAD:
-			fee.Add(fee, StoreFee)
-		case oEXTRO, oBALANCE:
-			fee.Add(fee, ExtroFee)
-		case oSHA256, oRIPEMD160, oECMUL, oECADD, oECSIGN, oECRECOVER, oECVALID:
-			fee.Add(fee, CryptoFee)
-		case oMKTX:
-			fee.Add(fee, ContractFee)
-		}
-
-		tf := new(big.Int).Add(fee, fee2)
-		if contract.Amount.Cmp(tf) < 0 {
-			fmt.Println("Insufficient fees to continue running the contract", tf, contract.Amount)
-			break
-		}
-		// Add the fee to the total fee. It's subtracted when we're done looping
-		totalFee.Add(totalFee, tf)
-
 		if ethutil.Config.Debug {
 			ethutil.Config.Log.Debugf("%-3d %-4s", pc, op.String())
 		}
 
+		// TODO Get each instruction cost properly
+		fee := new(big.Int)
+		fee.Add(fee, big.NewInt(1000))
+
+		if closure.Gas.Cmp(fee) < 0 {
+			return closure.Return(nil)
+		}
+
 		switch op {
-		case oSTOP:
-			fmt.Println("")
-			break out
+		case oLOG:
+			stack.Print()
+			mem.Print()
+		case oSTOP: // Stop the closure
+			return closure.Return(nil)
+
+		// 0x20 range
 		case oADD:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// (x + y) % 2 ** 256
 			base.Add(x, y)
 			base.Mod(base, Pow256)
 			// Pop result back on the stack
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oSUB:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// (x - y) % 2 ** 256
 			base.Sub(x, y)
 			base.Mod(base, Pow256)
 			// Pop result back on the stack
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oMUL:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// (x * y) % 2 ** 256
 			base.Mul(x, y)
 			base.Mod(base, Pow256)
 			// Pop result back on the stack
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oDIV:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// floor(x / y)
 			base.Div(x, y)
 			// Pop result back on the stack
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oSDIV:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// n > 2**255
 			if x.Cmp(Pow256) > 0 {
 				x.Sub(Pow256, x)
@@ -147,13 +127,13 @@ out:
 				z.Sub(Pow256, z)
 			}
 			// Push result on to the stack
-			vm.stack.Push(z)
+			stack.Push(z)
 		case oMOD:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			base.Mod(x, y)
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oSMOD:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// n > 2**255
 			if x.Cmp(Pow256) > 0 {
 				x.Sub(Pow256, x)
@@ -167,250 +147,189 @@ out:
 				z.Sub(Pow256, z)
 			}
 			// Push result on to the stack
-			vm.stack.Push(z)
+			stack.Push(z)
 		case oEXP:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			base.Exp(x, y, Pow256)
 
-			vm.stack.Push(base)
+			stack.Push(base)
 		case oNEG:
-			base.Sub(Pow256, vm.stack.Pop())
-			vm.stack.Push(base)
+			base.Sub(Pow256, stack.Pop())
+			stack.Push(base)
 		case oLT:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// x < y
 			if x.Cmp(y) < 0 {
-				vm.stack.Push(ethutil.BigTrue)
+				stack.Push(ethutil.BigTrue)
 			} else {
-				vm.stack.Push(ethutil.BigFalse)
-			}
-		case oLE:
-			x, y := vm.stack.Popn()
-			// x <= y
-			if x.Cmp(y) < 1 {
-				vm.stack.Push(ethutil.BigTrue)
-			} else {
-				vm.stack.Push(ethutil.BigFalse)
+				stack.Push(ethutil.BigFalse)
 			}
 		case oGT:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// x > y
 			if x.Cmp(y) > 0 {
-				vm.stack.Push(ethutil.BigTrue)
+				stack.Push(ethutil.BigTrue)
 			} else {
-				vm.stack.Push(ethutil.BigFalse)
-			}
-		case oGE:
-			x, y := vm.stack.Popn()
-			// x >= y
-			if x.Cmp(y) > -1 {
-				vm.stack.Push(ethutil.BigTrue)
-			} else {
-				vm.stack.Push(ethutil.BigFalse)
+				stack.Push(ethutil.BigFalse)
 			}
 		case oNOT:
-			x, y := vm.stack.Popn()
+			x, y := stack.Popn()
 			// x != y
 			if x.Cmp(y) != 0 {
-				vm.stack.Push(ethutil.BigTrue)
+				stack.Push(ethutil.BigTrue)
 			} else {
-				vm.stack.Push(ethutil.BigFalse)
-			}
-		case oMYADDRESS:
-			vm.stack.Push(ethutil.BigD(addr))
-		case oTXSENDER:
-			vm.stack.Push(ethutil.BigD(vars.sender))
-		case oTXVALUE:
-			vm.stack.Push(vars.txValue)
-		case oTXDATAN:
-			vm.stack.Push(big.NewInt(int64(len(vars.txData))))
-		case oTXDATA:
-			v := vm.stack.Pop()
-			// v >= len(data)
-			if v.Cmp(big.NewInt(int64(len(vars.txData)))) >= 0 {
-				vm.stack.Push(ethutil.Big("0"))
-			} else {
-				vm.stack.Push(ethutil.Big(vars.txData[v.Uint64()]))
-			}
-		case oBLK_PREVHASH:
-			vm.stack.Push(ethutil.BigD(vars.prevHash))
-		case oBLK_COINBASE:
-			vm.stack.Push(ethutil.BigD(vars.coinbase))
-		case oBLK_TIMESTAMP:
-			vm.stack.Push(big.NewInt(vars.time))
-		case oBLK_NUMBER:
-			vm.stack.Push(big.NewInt(int64(vars.blockNumber)))
-		case oBLK_DIFFICULTY:
-			vm.stack.Push(vars.diff)
-		case oBASEFEE:
-			// e = 10^21
-			e := big.NewInt(0).Exp(big.NewInt(10), big.NewInt(21), big.NewInt(0))
-			d := new(big.Rat)
-			d.SetInt(vars.diff)
-			c := new(big.Rat)
-			c.SetFloat64(0.5)
-			// d = diff / 0.5
-			d.Quo(d, c)
-			// base = floor(d)
-			base.Div(d.Num(), d.Denom())
-
-			x := new(big.Int)
-			x.Div(e, base)
-
-			// x = floor(10^21 / floor(diff^0.5))
-			vm.stack.Push(x)
-		case oSHA256, oSHA3, oRIPEMD160:
-			// This is probably save
-			// ceil(pop / 32)
-			length := int(math.Ceil(float64(vm.stack.Pop().Uint64()) / 32.0))
-			// New buffer which will contain the concatenated popped items
-			data := new(bytes.Buffer)
-			for i := 0; i < length; i++ {
-				// Encode the number to bytes and have it 32bytes long
-				num := ethutil.NumberToBytes(vm.stack.Pop().Bytes(), 256)
-				data.WriteString(string(num))
+				stack.Push(ethutil.BigFalse)
 			}
 
-			if op == oSHA256 {
-				vm.stack.Push(base.SetBytes(ethutil.Sha256Bin(data.Bytes())))
-			} else if op == oSHA3 {
-				vm.stack.Push(base.SetBytes(ethutil.Sha3Bin(data.Bytes())))
-			} else {
-				vm.stack.Push(base.SetBytes(ethutil.Ripemd160(data.Bytes())))
-			}
-		case oECMUL:
-			y := vm.stack.Pop()
-			x := vm.stack.Pop()
-			//n := vm.stack.Pop()
+		// 0x10 range
+		case oAND:
+		case oOR:
+		case oXOR:
+		case oBYTE:
 
-			//if ethutil.Big(x).Cmp(ethutil.Big(y)) {
-			data := new(bytes.Buffer)
-			data.WriteString(x.String())
-			data.WriteString(y.String())
-			if secp256k1.VerifyPubkeyValidity(data.Bytes()) == 1 {
-				// TODO
-			} else {
-				// Invalid, push infinity
-				vm.stack.Push(ethutil.Big("0"))
-				vm.stack.Push(ethutil.Big("0"))
-			}
-			//} else {
-			//	// Invalid, push infinity
-			//	vm.stack.Push("0")
-			//	vm.stack.Push("0")
-			//}
+		// 0x20 range
+		case oSHA3:
 
-		case oECADD:
-		case oECSIGN:
-		case oECRECOVER:
-		case oECVALID:
-		case oPUSH:
-			pc++
-			vm.stack.Push(contract.GetMem(pc).BigInt())
-		case oPOP:
-			// Pop current value of the stack
-			vm.stack.Pop()
-		case oDUP:
-			// Dup top stack
-			x := vm.stack.Pop()
-			vm.stack.Push(x)
-			vm.stack.Push(x)
-		case oSWAP:
-			// Swap two top most values
-			x, y := vm.stack.Popn()
-			vm.stack.Push(y)
-			vm.stack.Push(x)
-		case oMLOAD:
-			x := vm.stack.Pop()
-			vm.stack.Push(vm.mem[x.String()])
-		case oMSTORE:
-			x, y := vm.stack.Popn()
-			vm.mem[x.String()] = y
-		case oSLOAD:
-			// Load the value in storage and push it on the stack
-			x := vm.stack.Pop()
-			// decode the object as a big integer
-			decoder := contract.Addr(x.Bytes())
-			if !decoder.IsNil() {
-				vm.stack.Push(decoder.BigInt())
-			} else {
-				vm.stack.Push(ethutil.BigFalse)
-			}
-		case oSSTORE:
-			// Store Y at index X
-			y, x := vm.stack.Popn()
-			addr := ethutil.BigToBytes(x, 256)
-			fmt.Printf(" => %x (%v) @ %v", y.Bytes(), y, ethutil.BigD(addr))
-			contract.SetAddr(addr, y)
-			//contract.State().Update(string(idx), string(y))
-		case oJMP:
-			x := int(vm.stack.Pop().Uint64())
-			// Set pc to x - 1 (minus one so the incrementing at the end won't effect it)
-			pc = x
-			pc--
-		case oJMPI:
-			x := vm.stack.Pop()
-			// Set pc to x if it's non zero
-			if x.Cmp(ethutil.BigFalse) != 0 {
-				pc = int(x.Uint64())
-				pc--
-			}
-		case oIND:
-			vm.stack.Push(big.NewInt(int64(pc)))
-		case oEXTRO:
-			memAddr := vm.stack.Pop()
-			contractAddr := vm.stack.Pop().Bytes()
-
-			// Push the contract's memory on to the stack
-			vm.stack.Push(contractMemory(state, contractAddr, memAddr))
+		// 0x30 range
+		case oADDRESS:
+			stack.Push(ethutil.BigD(closure.Object().Address()))
 		case oBALANCE:
-			// Pushes the balance of the popped value on to the stack
-			account := state.GetAccount(vm.stack.Pop().Bytes())
-			vm.stack.Push(account.Amount)
-		case oMKTX:
-			addr, value := vm.stack.Popn()
-			from, length := vm.stack.Popn()
+			stack.Push(closure.Value)
+		case oORIGIN:
+			stack.Push(ethutil.BigD(vm.vars.origin))
+		case oCALLER:
+			stack.Push(ethutil.BigD(closure.Callee().Address()))
+		case oCALLVALUE:
+			// FIXME: Original value of the call, not the current value
+			stack.Push(closure.Value)
+		case oCALLDATA:
+			offset := stack.Pop()
+			mem.Set(offset.Int64(), int64(len(closure.Args)), closure.Args)
+		case oCALLDATASIZE:
+			stack.Push(big.NewInt(int64(len(closure.Args))))
+		case oGASPRICE:
+			// TODO
 
-			makeInlineTx(addr.Bytes(), value, from, length, contract, state)
+		// 0x40 range
+		case oPREVHASH:
+			stack.Push(ethutil.BigD(vm.vars.prevHash))
+		case oCOINBASE:
+			stack.Push(ethutil.BigD(vm.vars.coinbase))
+		case oTIMESTAMP:
+			stack.Push(big.NewInt(vm.vars.time))
+		case oNUMBER:
+			stack.Push(big.NewInt(int64(vm.vars.blockNumber)))
+		case oDIFFICULTY:
+			stack.Push(vm.vars.diff)
+		case oGASLIMIT:
+			// TODO
+
+		// 0x50 range
+		case oPUSH: // Push PC+1 on to the stack
+			pc.Add(pc, ethutil.Big1)
+
+			val := closure.GetMem(pc).BigInt()
+			stack.Push(val)
+		case oPOP:
+			stack.Pop()
+		case oDUP:
+			stack.Push(stack.Peek())
+		case oSWAP:
+			x, y := stack.Popn()
+			stack.Push(y)
+			stack.Push(x)
+		case oMLOAD:
+			offset := stack.Pop()
+			stack.Push(ethutil.BigD(mem.Get(offset.Int64(), 32)))
+		case oMSTORE: // Store the value at stack top-1 in to memory at location stack top
+			// Pop value of the stack
+			val, mStart := stack.Popn()
+			mem.Set(mStart.Int64(), 32, ethutil.BigToBytes(val, 256))
+		case oMSTORE8:
+			val, mStart := stack.Popn()
+			base.And(val, new(big.Int).SetInt64(0xff))
+			mem.Set(mStart.Int64(), 32, ethutil.BigToBytes(base, 256))
+		case oSLOAD:
+			loc := stack.Pop()
+			val := closure.GetMem(loc)
+			stack.Push(val.BigInt())
+		case oSSTORE:
+			val, loc := stack.Popn()
+			closure.SetMem(loc, ethutil.NewValue(val))
+		case oJUMP:
+			pc = stack.Pop()
+		case oJUMPI:
+			pos, cond := stack.Popn()
+			if cond.Cmp(big.NewInt(0)) > 0 {
+				pc = pos
+			}
+		case oPC:
+			stack.Push(pc)
+		case oMSIZE:
+			stack.Push(big.NewInt(int64(mem.Len())))
+		// 0x60 range
+		case oCALL:
+			// Pop return size and offset
+			retSize, retOffset := stack.Popn()
+			// Pop input size and offset
+			inSize, inOffset := stack.Popn()
+			// Get the arguments from the memory
+			args := mem.Get(inOffset.Int64(), inSize.Int64())
+			// Pop gas and value of the stack.
+			gas, value := stack.Popn()
+			// Closure addr
+			addr := stack.Pop()
+			// Fetch the contract which will serve as the closure body
+			contract := vm.state.GetContract(addr.Bytes())
+			// Create a new callable closure
+			closure := NewClosure(closure, contract, vm.state, gas, value)
+			// Executer the closure and get the return value (if any)
+			ret := closure.Call(vm, args)
+
+			mem.Set(retOffset.Int64(), retSize.Int64(), ret)
+		case oRETURN:
+			size, offset := stack.Popn()
+			ret := mem.Get(offset.Int64(), size.Int64())
+
+			return closure.Return(ret)
 		case oSUICIDE:
-			recAddr := vm.stack.Pop().Bytes()
-			// Purge all memory
-			deletedMemory := contract.state.Purge()
-			// Add refunds to the pop'ed address
-			refund := new(big.Int).Mul(StoreFee, big.NewInt(int64(deletedMemory)))
-			account := state.GetAccount(recAddr)
-			account.Amount.Add(account.Amount, refund)
-			// Update the refunding address
-			state.UpdateAccount(recAddr, account)
-			// Delete the contract
-			state.trie.Update(string(addr), "")
+			/*
+				recAddr := stack.Pop().Bytes()
+				// Purge all memory
+				deletedMemory := contract.state.Purge()
+				// Add refunds to the pop'ed address
+				refund := new(big.Int).Mul(StoreFee, big.NewInt(int64(deletedMemory)))
+				account := state.GetAccount(recAddr)
+				account.Amount.Add(account.Amount, refund)
+				// Update the refunding address
+				state.UpdateAccount(recAddr, account)
+				// Delete the contract
+				state.trie.Update(string(addr), "")
 
-			ethutil.Config.Log.Debugf("(%d) => %x\n", deletedMemory, recAddr)
-			break out
+				ethutil.Config.Log.Debugf("(%d) => %x\n", deletedMemory, recAddr)
+				break out
+			*/
 		default:
-			fmt.Printf("Invalid OPCODE: %x\n", op)
+			ethutil.Config.Log.Debugln("Invalid opcode", op)
 		}
-		ethutil.Config.Log.Debugln("")
-		//vm.stack.Print()
-		pc++
-	}
 
-	state.UpdateContract(addr, contract)
+		pc.Add(pc, ethutil.Big1)
+	}
 }
 
 func makeInlineTx(addr []byte, value, from, length *big.Int, contract *Contract, state *State) {
 	ethutil.Config.Log.Debugf(" => creating inline tx %x %v %v %v", addr, value, from, length)
-	j := 0
+	j := int64(0)
 	dataItems := make([]string, int(length.Uint64()))
-	for i := from.Uint64(); i < length.Uint64(); i++ {
-		dataItems[j] = contract.GetMem(j).Str()
+	for i := from.Int64(); i < length.Int64(); i++ {
+		dataItems[j] = contract.GetMem(big.NewInt(j)).Str()
 		j++
 	}
 
 	tx := NewTransaction(addr, value, dataItems)
 	if tx.IsContract() {
 		contract := MakeContract(tx, state)
-		state.UpdateContract(tx.Hash()[12:], contract)
+		state.UpdateContract(contract)
 	} else {
 		account := state.GetAccount(tx.Recipient)
 		account.Amount.Add(account.Amount, tx.Value)
diff --git a/ethchain/vm_test.go b/ethchain/vm_test.go
index 6ceb0ff15..047531e09 100644
--- a/ethchain/vm_test.go
+++ b/ethchain/vm_test.go
@@ -1,13 +1,15 @@
 package ethchain
 
 import (
-	"fmt"
+	"bytes"
 	"github.com/ethereum/eth-go/ethdb"
 	"github.com/ethereum/eth-go/ethutil"
 	"math/big"
 	"testing"
 )
 
+/*
+
 func TestRun(t *testing.T) {
 	InitFees()
 
@@ -104,3 +106,69 @@ func TestRun2(t *testing.T) {
 		txData:      tx.Data,
 	})
 }
+*/
+
+// XXX Full stack test
+func TestRun3(t *testing.T) {
+	ethutil.ReadConfig("")
+
+	db, _ := ethdb.NewMemDatabase()
+	state := NewState(ethutil.NewTrie(db, ""))
+
+	script := Compile([]string{
+		"PUSH", "300",
+		"PUSH", "0",
+		"MSTORE",
+
+		"PUSH", "32",
+		"CALLDATA",
+
+		"PUSH", "64",
+		"PUSH", "0",
+		"RETURN",
+	})
+	tx := NewTransaction(ContractAddr, ethutil.Big("100000000000000000000000000000000000000000000000000"), script)
+	addr := tx.Hash()[12:]
+	contract := MakeContract(tx, state)
+	state.UpdateContract(contract)
+
+	callerScript := ethutil.Compile(
+		"PUSH", 1337, // Argument
+		"PUSH", 65, // argument mem offset
+		"MSTORE",
+		"PUSH", 64, // ret size
+		"PUSH", 0, // ret offset
+
+		"PUSH", 32, // arg size
+		"PUSH", 65, // arg offset
+		"PUSH", 1000, /// Gas
+		"PUSH", 0, /// value
+		"PUSH", addr, // Sender
+		"CALL",
+		"PUSH", 64,
+		"PUSH", 0,
+		"RETURN",
+	)
+	callerTx := NewTransaction(ContractAddr, ethutil.Big("100000000000000000000000000000000000000000000000000"), callerScript)
+
+	// Contract addr as test address
+	account := NewAccount(ContractAddr, big.NewInt(10000000))
+	callerClosure := NewClosure(account, MakeContract(callerTx, state), state, big.NewInt(1000000000), new(big.Int))
+
+	vm := NewVm(state, RuntimeVars{
+		origin:      account.Address(),
+		blockNumber: 1,
+		prevHash:    ethutil.FromHex("5e20a0453cecd065ea59c37ac63e079ee08998b6045136a8ce6635c7912ec0b6"),
+		coinbase:    ethutil.FromHex("2adc25665018aa1fe0e6bc666dac8fc2697ff9ba"),
+		time:        1,
+		diff:        big.NewInt(256),
+		// XXX Tx data? Could be just an argument to the closure instead
+		txData: nil,
+	})
+	ret := callerClosure.Call(vm, nil)
+
+	exp := []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 44, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 57}
+	if bytes.Compare(ret, exp) != 0 {
+		t.Errorf("expected return value to be %v, got %v", exp, ret)
+	}
+}
diff --git a/ethutil/common.go b/ethutil/common.go
index 07df6bb13..f15b10e6d 100644
--- a/ethutil/common.go
+++ b/ethutil/common.go
@@ -33,3 +33,9 @@ func CurrencyToString(num *big.Int) string {
 
 	return fmt.Sprintf("%v Wei", num)
 }
+
+var (
+	Big1   = big.NewInt(1)
+	Big0   = big.NewInt(0)
+	Big256 = big.NewInt(0xff)
+)
diff --git a/ethutil/config.go b/ethutil/config.go
index 5fdc8e1c5..54b066fb9 100644
--- a/ethutil/config.go
+++ b/ethutil/config.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"os/user"
 	"path"
+	"runtime"
 )
 
 type LogType byte
@@ -19,12 +20,13 @@ const (
 type config struct {
 	Db Database
 
-	Log      *Logger
-	ExecPath string
-	Debug    bool
-	Ver      string
-	Pubkey   []byte
-	Seed     bool
+	Log          *Logger
+	ExecPath     string
+	Debug        bool
+	Ver          string
+	ClientString string
+	Pubkey       []byte
+	Seed         bool
 }
 
 var Config *config
@@ -48,11 +50,16 @@ func ReadConfig(base string) *config {
 
 		Config = &config{ExecPath: path, Debug: true, Ver: "0.3.1"}
 		Config.Log = NewLogger(LogFile|LogStd, LogLevelDebug)
+		Config.SetClientString("/Ethereum(G)")
 	}
 
 	return Config
 }
 
+func (c *config) SetClientString(str string) {
+	Config.ClientString = fmt.Sprintf("%s nv%s/%s", str, c.Ver, runtime.GOOS)
+}
+
 type LoggerType byte
 
 const (
diff --git a/ethutil/parsing.go b/ethutil/parsing.go
index 553bb9717..8929f0829 100644
--- a/ethutil/parsing.go
+++ b/ethutil/parsing.go
@@ -7,57 +7,72 @@ import (
 
 // Op codes
 var OpCodes = map[string]byte{
-	"STOP":           0x00,
-	"ADD":            0x01,
-	"MUL":            0x02,
-	"SUB":            0x03,
-	"DIV":            0x04,
-	"SDIV":           0x05,
-	"MOD":            0x06,
-	"SMOD":           0x07,
-	"EXP":            0x08,
-	"NEG":            0x09,
-	"LT":             0x0a,
-	"LE":             0x0b,
-	"GT":             0x0c,
-	"GE":             0x0d,
-	"EQ":             0x0e,
-	"NOT":            0x0f,
-	"MYADDRESS":      0x10,
-	"TXSENDER":       0x11,
-	"TXVALUE":        0x12,
-	"TXDATAN":        0x13,
-	"TXDATA":         0x14,
-	"BLK_PREVHASH":   0x15,
-	"BLK_COINBASE":   0x16,
-	"BLK_TIMESTAMP":  0x17,
-	"BLK_NUMBER":     0x18,
-	"BLK_DIFFICULTY": 0x19,
-	"BLK_NONCE":      0x1a,
-	"BASEFEE":        0x1b,
-	"SHA256":         0x20,
-	"RIPEMD160":      0x21,
-	"ECMUL":          0x22,
-	"ECADD":          0x23,
-	"ECSIGN":         0x24,
-	"ECRECOVER":      0x25,
-	"ECVALID":        0x26,
-	"SHA3":           0x27,
-	"PUSH":           0x30,
-	"POP":            0x31,
-	"DUP":            0x32,
-	"SWAP":           0x33,
-	"MLOAD":          0x34,
-	"MSTORE":         0x35,
-	"SLOAD":          0x36,
-	"SSTORE":         0x37,
-	"JMP":            0x38,
-	"JMPI":           0x39,
-	"IND":            0x3a,
-	"EXTRO":          0x3b,
-	"BALANCE":        0x3c,
-	"MKTX":           0x3d,
-	"SUICIDE":        0x3f,
+	// 0x0 range - arithmetic ops
+	"STOP": 0x00,
+	"ADD":  0x01,
+	"MUL":  0x02,
+	"SUB":  0x03,
+	"DIV":  0x04,
+	"SDIV": 0x05,
+	"MOD":  0x06,
+	"SMOD": 0x07,
+	"EXP":  0x08,
+	"NEG":  0x09,
+	"LT":   0x0a,
+	"GT":   0x0b,
+	"EQ":   0x0c,
+	"NOT":  0x0d,
+
+	// 0x10 range - bit ops
+	"AND":  0x10,
+	"OR":   0x11,
+	"XOR":  0x12,
+	"BYTE": 0x13,
+
+	// 0x20 range - crypto
+	"SHA3": 0x20,
+
+	// 0x30 range - closure state
+	"ADDRESS":      0x30,
+	"BALANCE":      0x31,
+	"ORIGIN":       0x32,
+	"CALLER":       0x33,
+	"CALLVALUE":    0x34,
+	"CALLDATA":     0x35,
+	"CALLDATASIZE": 0x36,
+	"GASPRICE":     0x38,
+
+	// 0x40 range - block operations
+	"PREVHASH":   0x40,
+	"COINBASE":   0x41,
+	"TIMESTAMP":  0x42,
+	"NUMBER":     0x43,
+	"DIFFICULTY": 0x44,
+	"GASLIMIT":   0x45,
+
+	// 0x50 range - 'storage' and execution
+	"PUSH":    0x50,
+	"POP":     0x51,
+	"DUP":     0x52,
+	"SWAP":    0x53,
+	"MLOAD":   0x54,
+	"MSTORE":  0x55,
+	"MSTORE8": 0x56,
+	"SLOAD":   0x57,
+	"SSTORE":  0x58,
+	"JUMP":    0x59,
+	"JUMPI":   0x5a,
+	"PC":      0x5b,
+	"MSIZE":   0x5c,
+
+	// 0x60 range - closures
+	"CREATE": 0x60,
+	"CALL":   0x61,
+	"RETURN": 0x62,
+
+	// 0x70 range - other
+	"LOG":     0x70,
+	"SUICIDE": 0x7f,
 }
 
 func IsOpCode(s string) bool {
@@ -69,16 +84,30 @@ func IsOpCode(s string) bool {
 	return false
 }
 
-func CompileInstr(s string) ([]byte, error) {
-	isOp := IsOpCode(s)
-	if isOp {
-		return []byte{OpCodes[s]}, nil
+func CompileInstr(s interface{}) ([]byte, error) {
+	switch s.(type) {
+	case string:
+		str := s.(string)
+		isOp := IsOpCode(str)
+		if isOp {
+			return []byte{OpCodes[str]}, nil
+		}
+
+		num := new(big.Int)
+		_, success := num.SetString(str, 0)
+		// Assume regular bytes during compilation
+		if !success {
+			num.SetBytes([]byte(str))
+		}
+
+		return num.Bytes(), nil
+	case int:
+		return big.NewInt(int64(s.(int))).Bytes(), nil
+	case []byte:
+		return BigD(s.([]byte)).Bytes(), nil
 	}
 
-	num := new(big.Int)
-	num.SetString(s, 0)
-
-	return num.Bytes(), nil
+	return nil, nil
 }
 
 func Instr(instr string) (int, []string, error) {
@@ -99,3 +128,17 @@ func Instr(instr string) (int, []string, error) {
 
 	return op, args[1:7], nil
 }
+
+// Script compilation functions
+// Compiles strings to machine code
+func Compile(instructions ...interface{}) (script []string) {
+	script = make([]string, len(instructions))
+
+	for i, val := range instructions {
+		instr, _ := CompileInstr(val)
+
+		script[i] = string(instr)
+	}
+
+	return
+}
diff --git a/ethutil/rlp.go b/ethutil/rlp.go
index e633f5f1d..33ec0d359 100644
--- a/ethutil/rlp.go
+++ b/ethutil/rlp.go
@@ -9,6 +9,10 @@ import (
 	"math/big"
 )
 
+type RlpEncodable interface {
+	RlpEncode() []byte
+}
+
 type RlpEncoder struct {
 	rlpData []byte
 }
diff --git a/ethutil/trie_test.go b/ethutil/trie_test.go
index 7c398f1de..79e5de921 100644
--- a/ethutil/trie_test.go
+++ b/ethutil/trie_test.go
@@ -1,6 +1,7 @@
 package ethutil
 
 import (
+	"fmt"
 	"reflect"
 	"testing"
 )
diff --git a/peer.go b/peer.go
index 22bbe7a4c..b8e75c686 100644
--- a/peer.go
+++ b/peer.go
@@ -7,7 +7,6 @@ import (
 	"github.com/ethereum/eth-go/ethutil"
 	"github.com/ethereum/eth-go/ethwire"
 	"net"
-	"runtime"
 	"strconv"
 	"strings"
 	"sync/atomic"
@@ -160,7 +159,7 @@ func NewOutboundPeer(addr string, ethereum *Ethereum, caps Caps) *Peer {
 		connected:   0,
 		disconnect:  0,
 		caps:        caps,
-		Version:     fmt.Sprintf("/Ethereum(G) v%s/%s", ethutil.Config.Ver, runtime.GOOS),
+		Version:     ethutil.Config.ClientString,
 	}
 
 	// Set up the connection in another goroutine so we don't block the main thread