The BTC ecosystem is advancing rapidly, with various programmability expansion solutions emerging.

Since the beginning of 2024, the technological development of the BTC ecosystem has shown an accelerated trend, particularly with significant progress in programmability expansion. This article will introduce several notable BTC expansion solutions, including Fractal Bitcoin, AVM, OP_NET, BRC100, and programmable runes.

Fractal

Fractal is a scalable framework virtualized based on the bitcoin core client software. It enhances the overall network performance by recursively creating a tree structure, fully compatible with Bitcoin and its infrastructure. Fractal activates the op_cat operator, allowing for more logic to be implemented.

Fractal is developed by the Unisat team and is expected to launch its mainnet in September 2024. Its token economics include 50% generated through mining, 15% for the ecosystem, 5% for early investor presales, 20% allocated to advisors and core contributors, and 10% for establishing partnerships and liquidity.

In terms of architectural design, Fractal encapsulates the bitcoin core client as a deployable blockchain software package (BCSP), recursively anchoring multiple BCSP instances to run on the Bitcoin mainnet. It makes some modifications to the bitcoin core, such as shortening the block confirmation time to 30 seconds and increasing the block size to 20MB.

Fractal has activated the op_cat operator, providing more exploration space for BTC scaling solutions. Assets can be transferred seamlessly between different layers, and BTC along with other mainnet assets can also exist as wrapped assets on Fractal.

Unlike Ethereum Layer 2, Fractal achieves computational scalability through virtualization while maintaining consistency with the main chain. It introduces a joint mining mechanism to enhance security, with one out of every three blocks generated through merged mining with BTC miners.

AVM

AVM(Atomicals Virtual Machine) is the BTC smart contract implementation of the Atomicals Protocol. It creates a virtual machine that simulates BTC scripts, opening up multiple raw BTC opcodes, allowing developers to implement smart contracts through Bitcoin script combinations.

AVM achieves Turing completeness through a dual-stack PDA, operating in a sandbox that includes an indexer, instruction parser, and global state. Its instruction set contains the complete BTC opcode, allowing developers to program using the functionalities of BTC that are not enabled.

AVM is an architecture that can be applied to any metadata protocol, such as BRC20, ARC20, Runes, CBRC, etc., with just minor adjustments to the indexer under the virtual machine. Currently, AVM has released a test version.

OP_NET

OP_NET aims to introduce Ethereum-like smart contract functionality to the Bitcoin network. It provides a complete, compact, and user-friendly development library, primarily written in AssemblyScript.

OP_NET retains Bitcoin's block consensus and data availability by executing complex computations on Bitcoin blocks through the virtual machine (OP_VM). It supports multiple programming languages and utilizes Tapscript to enable advanced smart contract functionalities.

When interacting on the OP_NET network, users need to pay an additional fee. To expand the use of BTC in DeFi applications, OP_NET provides a Proof of Authority system that allows BTC to be wrapped as WBTC.

The OP_NET ecosystem covers multiple areas including decentralized trading, lending, market making, liquidity provision, and cross-chain bridges, featuring projects such as Motoswap, Stash, Ordinal Novus, and Ichigai.

BRC100

BRC-100 is a decentralized computing protocol built on the Ordinals theory. It enables complex DeFi operations by adding new functions like "burn" and "mint" to brc20. Developers can expand more operators based on the BRC-100 protocol.

BRC-100 provides operations such as mint2/mint3 and burn2/burn3, allowing tokens to be converted between the UTXO model and state machine model. It supports extensibility and compatibility, and all BRC-100 extension protocols are mutually compatible.

The BRC-100 ecosystem includes projects such as inBRC, 100Swap, and 100Layer, covering areas such as markets, indexers, AMM exchanges, and liquidity protocols.

Programmability Runes ( Protorunes )

Programmable runes are an extension layer of runes, allowing the creation of programmable assets with runes. The Proto-Runes Protocol is the main project that provides a framework for programmable runes.

The Proto-Runes Protocol converts runes into programmable forms called Protorunes through the Protoburn mechanism. Protomessage is used to execute operational instructions within sub-protocols. The protocol supports complex operations such as AMM, lending, and more.

Currently, the first Protorune - QUORUM•GENESIS•PROTORUNE has successfully completed Protoburn, providing a functional model for implementing on-chain governance on Bitcoin L1.

The emergence of these expansion solutions demonstrates the rapid development of the BTC ecosystem at the technical level, bringing more possibilities and application scenarios to the Bitcoin network.