> For the complete documentation index, see [llms.txt](https://docs.alpenlabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.alpenlabs.io/how-alpen-works/specifications.md).

# Specifications

This document is *not* a full system spec, it's instead intended to be a brief description of externally-facing behavior that is useful for application developers.

## Consensus parameters <a href="#consensus-parameters" id="consensus-parameters"></a>

<table><thead><tr><th width="373"></th><th></th></tr></thead><tbody><tr><td><strong>Block time</strong></td><td>5 seconds</td></tr><tr><td><strong>Block gas limit</strong></td><td>36,000,000</td></tr><tr><td><strong>EVM Chain ID</strong></td><td>8150</td></tr></tbody></table>

These numbers will change in the future as Alpen's design evolves.

## Upstream precompiles <a href="#upstream-precompiles" id="upstream-precompiles"></a>

All upstream precompiles supported as of Prague, except `0x0a` for KZG proofs.

See [execution-specs](https://github.com/ethereum/execution-specs?tab=readme-ov-file#ethereum-protocol-releases) or [evm.codes/precompiled](https://www.evm.codes/precompiled?fork=prague) for more information.

## Other notable addresses <a href="#other-notable-addresses" id="other-notable-addresses"></a>

* `0x5400000000000000000000000000000000000001`: Bridge withdrawal precompile. See the [bridge documentation](/how-alpen-works/bitcoin-bridge.md) for more information.
* `0x5400000000000000000000000000000000000002`: Schnorr signature verification precompile.&#x20;


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