<p>As mentioned <a href="http://en.bitcoin.it/wiki/Transaction#Generation" rel="nofollow noreferrer">here</a>, <code>ffff001d</code> is the &quot;bits&quot; (representing the current difficulty target), and the rest is called the &quot;extra nonce&quot;, used to add more possibilities for mining than just the nonce field. This is also discuss here:
<a href="https://bitcoin.stackexchange.com/q/13122/51948">ScriptSig (coinbase) structure of the Genesis Block</a></p>
<p>Later, BIP 34 required that the coinbase include the block height, but this doesn't happen until after block 227,835.</p>

CC BY-SA 4.0
2022-01-25T17:54:28.417Z
I'm really surprised to learn that the very first block had extra nonce space, I always assumed that the extra nonce space was needed later, when the difficulty got very high. It makes me wonder why satoshi didn't allocate another few bytes in the header to nonce space. Does anyone know why the difficulty target was included?
Casey Rodarmor
CC BY-SA 4.0
2022-01-25T09:38:57.857Z
2022-01-25T12:31:57.160Z
2022-01-25T12:31:57.160Z
meshcollider
<p>Early blocks contain OP_PUSHBYTES sequences in the coinbase input ScriptSig:</p>
<ul>
<li>Block 1: <code>OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 04</code></li>
<li>Block 2: <code>OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 0b</code></li>
<li>Block 3: <code>OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 0e</code></li>
<li>Block 4: <code>OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 1a</code></li>
</ul>
<p>Do we know why?</p>

<block><coinbase-transaction><satoshi-nakamoto>
Why do early blocks contain OP_PUSHBYTES instructions in the coinbase input?
Casey Rodarmor
# Why do early blocks contain OP_PUSHBYTES instructions in the coinbase input?

(Asked by: username_0 on 2022-01-25)

Early blocks contain OP\_PUSHBYTES sequences in the coinbase input ScriptSig:

* Block 1: `OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 04`
* Block 2: `OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 0b`
* Block 3: `OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 0e`
* Block 4: `OP_PUSHBYTES_4 ffff001d OP_PUSHBYTES_1 1a`

Do we know why?

**Tags:** block, coinbase-transaction, satoshi-nakamoto


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## 1 answers

### Answer by username_1 on 2022-01-25. Score: 3

As mentioned [here](http://en.bitcoin.it/wiki/Transaction#Generation), `ffff001d` is the "bits" (representing the current difficulty target), and the rest is called the "extra nonce", used to add more possibilities for mining than just the nonce field. This is also discuss here:
[ScriptSig (coinbase) structure of the Genesis Block](https://bitcoin.stackexchange.com/q/13122/51948)

Later, BIP 34 required that the coinbase include the block height, but this doesn't happen until after block 227,835.

> **Comments:**
> **username_0**: I'm really surprised to learn that the very first block had extra nonce space, I always assumed that the extra nonce space was needed later, when the difficulty got very high. It makes me wonder why satoshi didn't allocate another few bytes in the header to nonce space. Does anyone know why the difficulty target was included?  

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