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> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
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# Hardfork.hasEIP4844

> Check if blob transactions (proto-danksharding) are available

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## EIP-4844 Features

**Active Since:** Cancun (March 13, 2024)

### Blob Transactions (Type 3)

**Transaction Format:**

* Type 3 transactions (blob-carrying)
* Up to 6 blobs per transaction (\~125KB each, total \~750KB)
* Blobs stored in consensus layer (not execution layer)
* Blobs pruned after \~18 days (4096 epochs)

**Blob Properties:**

* Size: 4096 field elements × 32 bytes = 131,072 bytes (\~128KB)
* Encoding: BLS12-381 field elements
* KZG commitments for data availability proofs

### New Opcodes

**BLOBHASH (0x49):**

* Pushes versioned hash of blob at given index
* Input: blob index (0-5)
* Returns: 32-byte versioned hash

**BLOBBASEFEE (0x4A):**

* Pushes current blob gas base fee
* Returns: blob base fee per gas

### Blob Gas Market

**Separate Fee Market:**

* Blob gas separate from execution gas
* Target: 3 blobs per block (393,216 blob gas)
* Maximum: 6 blobs per block (786,432 blob gas)
* Base fee adjustment: EIP-1559-style mechanism

**Pricing:**

* Independent blob base fee (starts at 1 wei)
* Exponential adjustment based on blob usage
* Much cheaper than calldata (\~10-100x reduction)

## Usage Patterns

### L2 Data Availability

Select cheapest L2 data posting method:

```typescript theme={null}
import { Hardfork } from 'tevm'

function selectL2DataMethod(fork: BrandedHardfork): string {
  if (fork.hasEIP4844()) {
    return "blobs"  // ~$0.01-0.10 per blob
  }

  return "calldata"  // ~$1-10 per equivalent data
}

// L2 rollups save 10-100x on data costs with blobs
```

### Transaction Type Selection

Choose appropriate transaction format:

```typescript theme={null}
import { Hardfork } from 'tevm'

function buildL2BatchSubmission(
  fork: BrandedHardfork,
  data: Uint8Array
) {
  if (fork.hasEIP4844() && data.length > 50_000) {
    return {
      type: 3,  // Blob transaction
      blobs: chunkIntoBlobs(data),
      maxFeePerBlobGas: estimateBlobFee()
    }
  }

  return {
    type: 2,  // EIP-1559
    data: data  // Expensive calldata
  }
}
```

### Gas Estimation

Calculate costs for blob vs calldata:

```typescript theme={null}
import { Hardfork } from 'tevm'

function estimateL2PostingCost(
  fork: BrandedHardfork,
  dataSize: number,
  blobBaseFee: bigint,
  gasPrice: bigint
): bigint {
  if (fork.hasEIP4844()) {
    // Blob cost
    const blobsNeeded = Math.ceil(dataSize / 131_072)
    const blobGas = BigInt(blobsNeeded) * 131_072n
    return blobGas * blobBaseFee
  }

  // Calldata cost (16 gas per non-zero byte)
  const calldataGas = BigInt(dataSize) * 16n
  return calldataGas * gasPrice
}
```

### Opcode Availability

Check blob-related opcodes:

```typescript theme={null}
import { Hardfork } from 'tevm'

function getBlobOpcodes(fork: BrandedHardfork) {
  if (fork.hasEIP4844()) {
    return {
      BLOBHASH: 0x49,
      BLOBBASEFEE: 0x4A
    }
  }

  return null  // Not available
}
```

### Smart Contract Integration

Access blob hashes in smart contracts:

```typescript theme={null}
import { Hardfork } from 'tevm'

function generateBlobHashLoader(fork: BrandedHardfork): Uint8Array {
  if (!fork.hasEIP4844()) {
    throw new Error("Blob transactions require Cancun or later")
  }

  // Generate bytecode: PUSH1 0, BLOBHASH
  return new Uint8Array([0x60, 0x00, 0x49])
}
```

## Network Configuration

Validate blob transaction support:

```typescript theme={null}
import { Hardfork, CANCUN } from 'tevm'

function validateBlobSupport(config: NetworkConfig) {
  const fork = Hardfork(config.hardfork)

  if (!fork.hasEIP4844()) {
    throw new Error(
      `Network ${config.name} does not support blob transactions. ` +
      `Requires Cancun or later, got ${Hardfork.toString(fork)}`
    )
  }
}
```

## EIP References

**Primary:**

* [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844) - Shard blob transactions

**Related:**

* [EIP-4788](https://eips.ethereum.org/EIPS/eip-4788) - Beacon block root in EVM
* [EIP-7516](https://eips.ethereum.org/EIPS/eip-7516) - BLOBBASEFEE opcode

**Cryptography:**

* KZG polynomial commitments (BLS12-381 curve)
* Point evaluation precompile at 0x0A

## Impact

**For L2 Rollups:**

* 10-100x cost reduction for data availability
* Enables higher throughput at lower cost
* Standard data availability layer for Ethereum L2s

**For Users:**

* Lower L2 transaction fees
* No direct impact on L1 transactions (separate fee market)

**For Developers:**

* Must handle Type 3 transactions
* Blob data only available for \~18 days (temporary storage)
* KZG commitments for data availability proofs
* New opcodes: BLOBHASH, BLOBBASEFEE

**For Validators:**

* Increased block size (\~125KB per blob, max 6 blobs)
* Separate blob gas fee market
* Blobs pruned from consensus layer after \~18 days

## See Also

* [hasEIP1153](/primitives/hardfork/has-eip1153) - Check transient storage availability (Cancun)
* [hasEIP1559](/primitives/hardfork/has-eip1559) - Check EIP-1559 base fee availability (London)
* [isAtLeast](/primitives/hardfork/is-at-least) - General version comparison