## Preamble

    EIP: 609
    Title: Hardfork Meta: Byzantium
    Author: Alex Beregszaszi
    Type: Standard Track
    Category: Core
    Status: Draft
    Created: 2017-04-23
    Requires: 100, 140, 196, 197, 198, 211, 214, 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 (Change difficulty adjustment to target mean block time including uncles)
  - EIP 140 (REVERT instruction in the Ethereum Virtual Machine)
  - EIP 196 (Precompiled contracts for addition and scalar multiplication on the elliptic curve alt_bn128)
  - EIP 197 (Precompiled contracts for optimal ate pairing check on the elliptic curve alt_bn128)
  - EIP 198 (Precompiled contract for bigint modular exponentiation)
  - EIP 211 (New opcodes: RETURNDATASIZE and RETURNDATACOPY)
  - EIP 214 (New opcode STATICCALL)
  - EIP 649 (Difficulty Bomb Delay and Block Reward Reduction)
  - EIP 658 (Embedding transaction return data in receipts)
  
## References

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

## Copyright

Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).