Bitcoin Universe · Model 02

The mining machine

A miner's whole job, opened up: build a block, then guess numbers until the block's fingerprint is small enough. Every guess here is a real double SHA-256; the target is an easy educational one.

Real hashing · simulated block

Educational difficulty

Simulated hash rate (real hashes per second in this page)

Mechanism 1 of 6

Block assembly

Readout

The 80-byte header

Field	Bytes	Serialized (little-endian)	Value

Scale check: this page runs up to 20,000 hashes per second. A single modern mining ASIC does on the order of 10¹⁴ per second, and the whole network hundreds of exahashes (10²⁰) per second. A mainnet target needs roughly 10²³–10²⁴ attempts per block on average, so real blocks are never found in a browser.

Data in flight, the nonce field, the valid zone and the found block The parts that compute Simulated block contents

Real: the header serialization, every SHA-256d and the integer comparison with the target. Educational: the transactions, previous block hash, timestamp and the target, which is set so a block takes hundreds or thousands of attempts instead of about 10²³. At up to 4 attempts per second each attempt is shown on its way through the machine; faster rates compute every attempt but only draw the latest.