---
eip: 609
title: "Hardfork Meta: Byzantium"
author: Alex Beregszaszi (@axic)
type: Meta
status: Final
created: 2017-04-23
requires: 100, 140, 196, 197, 198, 211, 214, 607, 649, 658
---

## Abstract

This specifies the changes included in the hard fork named Byzantium.

## Specification

- Codename: Byzantium
- Aliases: Metropolis/Byzantium, Metropolis part 1
- Activation:
  - Block >= 4,370,000 on Mainnet
  - Block >= 1,700,000 on Ropsten testnet
- Included EIPs:
  - [EIP-100](./eip-100.md) (Change difficulty adjustment to target mean block time including uncles)
  - [EIP-140](./eip-140.md) (REVERT instruction in the Ethereum Virtual Machine)
  - [EIP-196](./eip-196.md) (Precompiled contracts for addition and scalar multiplication on the elliptic curve alt_bn128)
  - [EIP-197](./eip-197.md) (Precompiled contracts for optimal ate pairing check on the elliptic curve alt_bn128)
  - [EIP-198](./eip-198.md) (Precompiled contract for bigint modular exponentiation)
  - [EIP-211](./eip-211.md) (New opcodes: RETURNDATASIZE and RETURNDATACOPY)
  - [EIP-214](./eip-214.md) (New opcode STATICCALL)
  - [EIP-649](./eip-649.md) (Difficulty Bomb Delay and Block Reward Reduction)
  - [EIP-658](./eip-658.md) (Embedding transaction status code in receipts)

## References

1. https://blog.ethereum.org/2017/10/12/byzantium-hf-announcement/

## Copyright

Copyright and related rights waived via [CC0](../LICENSE.md).