diff --git a/generators/default.json b/generators/default.json
new file mode 100644
index 000000000..181a9dd54
--- /dev/null
+++ b/generators/default.json
@@ -0,0 +1,56 @@
+{
+	"genesisGasLimit": { "v": 1000000, "d": "Gas limit of the Genesis block." },
+	"minGasLimit": { "v": 125000, "d": "Minimum the gas limit may ever be." },
+	"gasLimitBoundDivisor": { "v": 1024, "d": "The bound divisor of the gas limit, used in update calculations." },
+	"genesisDifficulty": { "v": 131072, "d": "Difficulty of the Genesis block." },
+	"minimumDifficulty": { "v": 131072, "d": "The minimum that the difficulty may ever be." },
+	"difficultyBoundDivisor": { "v": 2048, "d": "The bound divisor of the difficulty, used in the update calculations." },
+	"durationLimit": { "v": 8, "d": "The decision boundary on the blocktime duration used to determine whether difficulty should go up or not." },
+	"maximumExtraDataSize": { "v": 1024, "d": "Maximum size extra data may be after Genesis." },
+	"epochDuration": { "v": 30000, "d": "Duration between proof-of-work epochs." },
+	"stackLimit": { "v": 1024, "d": "Maximum size of VM stack allowed." },
+
+	"tierStepGas": { "v": [ 0, 2, 3, 5, 8, 10, 20 ], "d": "Once per operation, for a selection of them." },
+	"expGas": { "v": 10, "d": "Once per EXP instuction." },
+	"expByteGas": { "v": 10, "d": "Times ceil(log256(exponent)) for the EXP instruction." },
+
+	"sha3Gas": { "v": 30, "d": "Once per SHA3 operation." },
+	"sha3WordGas": { "v": 6, "d": "Once per word of the SHA3 operation's data." },
+
+	"sloadGas": { "v": 50, "d": "Multiplied by the number of 32-byte words that are copied (round up) for any *COPY operation and added." },
+	"sstoreSetGas": { "v": 20000, "d": "Once per SLOAD operation." },
+	"sstoreResetGas": { "v": 5000, "d": "Once per SSTORE operation if the zeroness changes from zero." },
+	"sstoreClearGas": { "v": 5000, "d": "Once per SSTORE operation if the zeroness doesn't change." },
+	"sstoreRefundGas": { "v": 15000, "d": "Once per SSTORE operation if the zeroness changes to zero." },
+	"jumpdestGas": { "v": 1, "d": "Refunded gas, once per SSTORE operation if the zeroness changes to zero." },
+
+	"logGas": { "v": 375, "d": "Per LOG* operation." },
+	"logDataGas": { "v": 8, "d": "Per byte in a LOG* operation's data." },
+	"logTopicGas": { "v": 375, "d": "Multiplied by the * of the LOG*, per LOG transaction. e.g. LOG0 incurs 0 * c_txLogTopicGas, LOG4 incurs 4 * c_txLogTopicGas." },
+
+	"createGas": { "v": 32000, "d": "Once per CREATE operation & contract-creation transaction." },
+
+	"callGas": { "v": 40, "d": "Once per CALL operation & message call transaction." },
+	"callStipend": { "v": 2300, "d": "Free gas given at beginning of call." },
+	"callValueTransferGas": { "v": 9000, "d": "Paid for CALL when the value transfor is non-zero." },
+	"callNewAccountGas": { "v": 25000, "d": "Paid for CALL when the destination address didn't exist prior." },
+
+	"suicideRefundGas": { "v": 24000, "d": "Refunded following a suicide operation." },
+	"memoryGas": { "v": 3, "d": "Times the address of the (highest referenced byte in memory + 1). NOTE: referencing happens on read, write and in instructions such as RETURN and CALL." },
+	"quadCoeffDiv": { "v": 512, "d": "Divisor for the quadratic particle of the memory cost equation." },
+
+	"createDataGas": { "v": 200, "d": "" },
+	"txGas": { "v": 21000, "d": "Per transaction. NOTE: Not payable on data of calls between transactions." },
+	"txDataZeroGas": { "v": 4, "d": "Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions." },
+	"txDataNonZeroGas": { "v": 68, "d": "Per byte of data attached to a transaction that is not equal to zero. NOTE: Not payable on data of calls between transactions." },
+
+	"copyGas": { "v": 3, "d": "" },
+	
+	"ecrecoverGas": { "v": 3000, "d": "" },
+	"sha256Gas": { "v": 60, "d": "" },
+	"sha256WordGas": { "v": 12, "d": "" },
+	"ripemd160Gas": { "v": 600, "d": "" },
+	"ripemd160WordGas": { "v": 120, "d": "" },
+	"identityGas": { "v": 15, "d": "" },
+	"identityWordGas": { "v": 3, "d": ""}
+}
diff --git a/generators/defaults.go b/generators/defaults.go
new file mode 100644
index 000000000..b0c71111c
--- /dev/null
+++ b/generators/defaults.go
@@ -0,0 +1,62 @@
+//go:generate go run defaults.go default.json defs.go
+
+package main //build !none
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path"
+	"strings"
+)
+
+func fatal(str string, v ...interface{}) {
+	fmt.Fprintf(os.Stderr, str, v...)
+	os.Exit(1)
+}
+
+type setting struct {
+	Value   int64  `json:"v"`
+	Comment string `json:"d"`
+}
+
+func main() {
+	if len(os.Args) < 3 {
+		fatal("usage %s <input> <output>\n", os.Args[0])
+	}
+
+	content, err := ioutil.ReadFile(os.Args[1])
+	if err != nil {
+		fatal("error reading file %v\n", err)
+	}
+
+	m := make(map[string]setting)
+	json.Unmarshal(content, &m)
+
+	filepath := path.Join(os.Getenv("GOPATH"), "src", "github.com", "ethereum", "go-ethereum", "core", os.Args[2])
+	output, err := os.OpenFile(filepath, os.O_RDWR|os.O_CREATE, os.ModePerm /*0777*/)
+	if err != nil {
+		fatal("error opening file for writing %v\n", err)
+	}
+
+	output.WriteString(`package core
+
+import "math/big"
+
+var (
+`)
+
+	for name, setting := range m {
+		output.WriteString(fmt.Sprintf("%s=big.NewInt(%d) // %s\n", strings.Title(name), setting.Value, setting.Comment))
+	}
+
+	output.WriteString(")\n")
+	output.Close()
+
+	cmd := exec.Command("gofmt", "-w", filepath)
+	if err := cmd.Run(); err != nil {
+		fatal("gofmt failed: %v\n", err)
+	}
+}