VM Differences

The Core Space VM is compatible with the EVM in most cases, but there are some differences. This page lists the differences between the two.

Address Calculation

The contract address calculation is different from Ethereum. Check Core Address for more details.

1820 Registry

The 1820 registry is a contract that stores the addresses of other contracts that implement certain interfaces. It is used to implement the EIP-1820 standard. The 1820 registry is deployed at Core Space hex40 address 0x88887eD889e776bCBe2f0f9932EcFaBcDfCd1820

Opcode

Before v2.4.0 the BLOCKHASH opcode can only take NUMBER-1 as input. (Unlike Ethereum, which takes any integer in NUMBER-256 to NUMBER-1 as input). Which means the Solidity built-in function blockhash can only take block.number - 1 as input.

After v2.4.0 it is fully compatible with Ethereum with an advanced input range up to 65536 blocks (implemented by CIP-133).

Block Gas Limit

The block gas limit is 30 million before v2.4.0 and 60 million gas after v2.4.0.

block.number

The block.number is the sequence number in whole tree-graph.

Internal Contracts

Core Space has some built-in internal contracts that are not in Ethereum.

Gas

1. Gas used and refund: Conflux requires less gas in SSTORE operation but no longer refunds resetting storage and contract destruction.
2. Gas Fee Refund: In Ethereum, if a transaction's gas limit exceeds the actual gas cost, the remaining gas is fully refunded. In contrast, Conflux refunds a maximum of 1/4 of the gas limit. Setting an excessively high gas limit in Conflux can lead to additional transaction fee costs. However, no extra fees are incurred if the gas limit is set to less than 4/3 of the actual cost. Therefore, providing an accurate gas estimate for a transaction is crucial for optimizing transaction fees.