# Precompiles

This page specifies precompile behavior in MegaETH. MegaETH inherits the standard precompile set from the underlying EVM baseline unless explicitly overridden on this page.

## Motivation

MegaETH also overrides the gas cost of selected precompiles to better match the actual computation they consume. If a precompile is materially underpriced, an attacker can pack many such calls into a transaction or block and impose disproportionate computation on the sequencer. The overrides on this page exist to reduce that denial-of-service risk by bringing charged gas closer to actual execution cost.

## Specification

A node MUST inherit the standard precompile set from the Optimism Isthmus / Ethereum Prague baseline except for the following MegaETH-specific overrides.

| Precompile           | Address | MegaETH-Specific Behavior                                                             |
| -------------------- | ------- | ------------------------------------------------------------------------------------- |
| KZG Point Evaluation | `0x0A`  | Fixed gas cost of `KZG_POINT_EVALUATION_GAS_COST`                                     |
| ModExp               | `0x05`  | Uses the Osaka / [EIP-7883](https://eips.ethereum.org/EIPS/eip-7883) pricing schedule |

For KZG Point Evaluation, if the supplied gas is less than `KZG_POINT_EVALUATION_GAS_COST`, the precompile MUST fail with `OutOfGas`. Otherwise the node MUST charge exactly `KZG_POINT_EVALUATION_GAS_COST` gas for the precompile.

For ModExp, the node MUST use the Osaka / [EIP-7883](https://eips.ethereum.org/EIPS/eip-7883) pricing schedule instead of the earlier inherited pricing schedule.

All other precompiles MUST behave according to the inherited EVM baseline unless explicitly overridden elsewhere in this specification.

## Constants

| Constant                        | Value   | Description                                            |
| ------------------------------- | ------- | ------------------------------------------------------ |
| `KZG_POINT_EVALUATION_GAS_COST` | 100,000 | Fixed gas cost for the KZG Point Evaluation precompile |

## Spec History

* [MiniRex](https://docs.megaeth.com/spec/network-upgrades/minirex) introduced the stable KZG Point Evaluation and ModExp overrides.
* [Rex](https://docs.megaeth.com/spec/network-upgrades/rex), [Rex1](https://docs.megaeth.com/spec/network-upgrades/rex1), [Rex2](https://docs.megaeth.com/spec/network-upgrades/rex2), and [Rex3](https://docs.megaeth.com/spec/network-upgrades/rex3) retain the same stable overrides.