Smart Contract Storage & Events

Call a Function

From Alice

To Bob

Amount 50

Ready — pick accounts and an amount, then call a function.

Contract State

Total Supply

950

Tx Count (nonce)

Gas Used (cum.)

Events Emitted

Event Log

How it works

A smart contract is code that lives at an on-chain address alongside its own persistent storage — here a mapping(address => uint256) balances slot per account plus a single uint256 totalSupply slot, exactly like a minimal ERC-20 token.

function transfer(to, amount):
    require(balances[msg.sender] >= amount)   // else REVERT, state unchanged
    balances[msg.sender] -= amount
    balances[to] += amount
    emit Transfer(msg.sender, to, amount)

function mint(to, amount):
    balances[to] += amount
    totalSupply += amount
    emit Transfer(address(0), to, amount)

function burn(from, amount):
    require(balances[from] >= amount)
    balances[from] -= amount
    totalSupply -= amount
    emit Transfer(from, address(0), amount)

Function call — a transaction invokes one function; the pillar heights in the scene are the actual storage values, so a successful call visibly rewrites state on-chain.
require() / revert — if a precondition fails (insufficient balance) the whole call reverts: no storage changes, but gas for the failed attempt is still spent, exactly as on Ethereum.
Gas — each opcode (SLOAD/SSTORE/LOG) costs gas; writing a fresh storage slot is the most expensive step, which is why mint/burn cost more here than a transfer between two already-used accounts.
Events — emit writes an entry to the transaction's log/receipt, not to contract storage; it's cheap, indexable off-chain, and is how wallets and block explorers know a transfer happened. The rising pulse and the Event Log list represent that log entry.

This is the same model every ERC-20 token, DEX, and lending protocol on Ethereum (and every EVM-compatible chain) is built from — millions of contracts differ only in which functions surround this storage + events pattern.

Contract storage core Account balance (pillar height) Event pulse (success) Reverted call

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