Execution model
So far, we’ve learned about the series of steps that have to happen for a transaction to execute from start to finish. Now, we’ll look at how the transaction actually executes within the VM.
The part of the protocol that actually handles processing the transactions is Ethereum’s own virtual machine, known as the Ethereum Virtual Machine (EVM).
The EVM is a Turing complete virtual machine, as defined earlier. The only limitation the EVM has that a typical Turing complete machine does not is that the EVM is intrinsically bound by gas. Thus, the total amount of computation that can be done is intrinsically limited by the amount of gas provided.
Image for post
Source: CMU
Moreover, the EVM has a stack-based architecture. A stack machine is a computer that uses a last-in, first-out stack to hold temporary values.
The size of each stack item in the EVM is 256-bit, and the stack has a maximum size of 1024.
The EVM has memory, where items are stored as word-addressed byte arrays. Memory is volatile, meaning it is not permanent.
The EVM also has storage. Unlike memory, storage is non-volatile and is maintained as part of the system state. The EVM stores program code separately, in a virtual ROM that can only be accessed via special instructions. In this way, the EVM differs from the typical von Neumann architecture, in which program code is stored in memory or storage.
Image for post
The EVM also has its own language: “EVM bytecode.” When a programmer like you or me writes smart contracts that operate on Ethereum, we typically write code in a higher-level language such as Solidity. We can then compile that down to EVM bytecode that the EVM can understand.
Okay, now on to execution.
Before executing a particular computation, the processor makes sure that the following information is available and valid:
System state
Remaining gas for computation
Address of the account that owns the code that is executing
Address of the sender of the transaction that originated this execution
Address of the account that caused the code to execute (could be different from the original sender)
Gas price of the transaction that originated this execution
Input data for this execution
Value (in Wei) passed to this account as part of the current execution
Machine code to be executed
Block header of the current block
Depth of the present message call or contract creation stack
At the start of execution, memory and stack are empty and the program counter is zero.
PC: 0 STACK: [] MEM: [], STORAGE: {}
The EVM then executes the transaction recursively, computing the system state and the machine state for each loop. The system state is simply Ethereum’s global state. The machine state is comprised of:
gas available
program counter
memory contents
active number of words in memory
stack contents.
Stack items are added or removed from the leftmost portion of the series.
On each cycle, the appropriate gas amount is reduced from the remaining gas, and the program counter increments.
At the end of each loop, there are three possibilities:
The machine reaches an exceptional state (e.g. insufficient gas, invalid instructions, insufficient stack items, stack items would overflow above 1024, invalid JUMP/JUMPI destination, etc.) and so must be halted, with any changes discarded
The sequence continues to process into the next loop
The machine reaches a controlled halt (the end of the execution process)
Assuming the execution doesn’t hit an exceptional state and reaches a “controlled” or normal halt, the machine generates the resultant state, the remaining gas after this execution, the accrued substate, and the resultant output.
Phew. We got through one of the most complex parts of Ethereum. Even if you didn’t fully comprehend this part, that’s okay. You don’t really need to understand the nitty gritty execution details unless you’re working at a very deep level.
How a block gets finalized
Finally, let’s look at how a block of many transactions gets finalized.
When we say “finalized,” it can mean two different things, depending on whether the block is new or existing. If it’s a new block, we’re referring to the process required for mining this block. If it’s an existing block, then we’re talking about the process of validating the block. In either case, there are four requirements for a block to be “finalized”:
1) Validate (or, if mining, determine) ommers
Each ommer block within the block header must be a valid header and be within the sixth generation of the present block.
2) Validate (or, if mining, determine) transactions
The gasUsed number on the block must be equal to the cumulative gas used by the transactions listed in the block. (Recall that when executing a transaction, we keep track of the block gas counter, which keeps track of the total gas used by all transactions in the block).
3) Apply rewards (only if mining)
The beneficiary address is awarded 5 Ether for mining the block. (Under Ethereum proposal EIP-649, this reward of 5 ETH will soon be reduced to 3 ETH). Additionally, for each ommer, the current block’s beneficiary is awarded an additional 1/32 of the current block reward. Lastly, the beneficiary of the ommer block(s) also gets awarded a certain amount (there’s a special formula for how this is calculated).
4) Verify (or, if mining, compute a valid) state and nonce
Ensure that all transactions and resultant state changes are applied, and then define the new block as the state after the block reward has been applied to the final transaction’s resultant state. Verification occurs by checking this final state against the state trie stored in the header.
'Crypto-' comes from the Ancient Greek κρυπτός kruptós, meaning 'hidden' or 'secret'. Crypto-anarchism refers to anarchist politics founded on cryptographic methods, as well as a form of anarchism that operates in secret.ethereum 1070 bitcoin миксеры
перспективы bitcoin
2048 bitcoin bitcoin price cryptocurrency wallet новые bitcoin monero алгоритм платформу ethereum video bitcoin There are many types of wallets you can use to keep your digital assets safe. Mobile and web-based wallets make frequent transactions easy. Hardware wallets are best suited for secure, long-term storage. When you’re choosing a crypto wallet, think of what you plan to do with your tokens. A wallet that best suits your needs is always the right choice.How To Invest In Litecoin (And Should You Do It)Global: The goal is for anyone in the world to be able to publish or use these dapps.удвоитель bitcoin txid ethereum script bitcoin monero форк bitcoin doge bitcoin 1000 bitcoin pay Digital: Cryptocurrency only exists on computers. There are no coins and no notes. There are no reserves for crypto in Fort Knox or the Bank of England!ethereum swarm bitcoin darkcoin bitcoin conveyor ethereum browser credit bitcoin ethereum difficulty
bitcoin alliance bestexchange bitcoin bitcoin paypal
collector bitcoin форумы bitcoin
протокол bitcoin bitcoin майнить
bitcoin получение Some speculators like cryptocurrencies because they’re going up in value and have no interest in the currencies’ long-term acceptance as a way to move moneybitcoin payza qr bitcoin remix ethereum kraken bitcoin scrypt bitcoin *****uminer monero криптовалюту monero foto bitcoin ethereum studio
bitcoin зебра алгоритмы ethereum microsoft ethereum cryptocurrency wallets china cryptocurrency hashrate bitcoin daily bitcoin atm bitcoin
flash bitcoin bitcoin обзор
usd bitcoin alpha bitcoin bitcoin 2048 Is the problem one of resources? In the whitepaper, Satoshi remarks:bitcoin plus monero address ethereum microsoft
партнерка bitcoin ethereum асик bitcoin heist
forex bitcoin bitcoin ваучер monero сложность пожертвование bitcoin сбербанк bitcoin What does this mean?bitcoin joker
bitcoin click сбор bitcoin
fun bitcoin bitcoin escrow проект ethereum bitcoin india ethereum investing bitcoin 50 bitcoin безопасность decred ethereum видео bitcoin alien bitcoin bitcoin mixer 50 bitcoin bitcoin xl panda bitcoin bitcoin sha256 jaxx monero donate bitcoin raiden ethereum bitcoin gadget plus bitcoin bitcoin bitrix кредиты bitcoin bitcoin exe hacking bitcoin сбор bitcoin bitcoin easy bitcoin криптовалюта bitcoin world ethereum php пул monero bitcoin dance bitcoin мониторинг usd bitcoin bitcoin значок bitcoin майнинга bitcoin 2017
валюта monero bitcoin card wifi tether logo ethereum 22 bitcoin p2pool bitcoin майнинг bitcoin monero github monero форк bitcoin рбк
bitcoin цены отследить bitcoin bitcoin сервисы bitcoin мастернода bitcoin roll water bitcoin
bitcoin forex tether обмен
bitcoin анализ monero *****uminer monero pools bitcoin футболка accept bitcoin monero новости bitcoin valet bitcoin рулетка ethereum ethash tether As you most likely already know, Bitcoin is a blockchain-based cryptocurrency. It essentially works similar to a bank’s ledger (record of transactions). However, banks need you to trust them. Bitcoin is different. You only need to trust the code that created the network, and its rules. It’s no coincidence that Bitcoin was created just after the global financial crisis of 2008. It’s been designed to be trust-less money!Note: Renewable energy is energy that is collected naturally. Think sun, wind, water, etc.ethereum testnet bitcoin pools bitcoin card flash bitcoin bitcoin софт lealana bitcoin ethereum купить
бонус bitcoin exchanges bitcoin Binance cryptocurrency trading platform logotether clockworkmod kinolix bitcoin перевод ethereum bitcoin currency
weather bitcoin создатель ethereum bitcoin like разработчик bitcoin
bitcoin инструкция bitcoin безопасность bitcoin qiwi bitcoin take bitcoin machine tether обмен bitcoin исходники bitcoin news обновление ethereum bitcoin iq bitcoin nodes spin bitcoin tether валюта ethereum api a form of retirement income. Annuities could be transferred to third partiesмайнинга bitcoin bitcoin mail Currently, the velocity of Bitcoin is much higher on average, but the problem is that a large portion of this velocity is just trading volume, not spending volume. For a medium of exchange, the vast majority of volume is from consumer spending, with only a small percentage of that volume involved with currency trading.bitcoin indonesia short bitcoin
bitcoin dark bitcoin example кости bitcoin майнинг monero bitcoin автоматически ethereum картинки
bitcoin автомат
bitcoin rt эфириум ethereum charts bitcoin bitcoin раздача ethereum перспективы приложения bitcoin bitcoin payoneer ethereum настройка bitcoin покупка flash bitcoin ethereum продам wikileaks bitcoin alliance bitcoin pay bitcoin steam bitcoin ledger bitcoin эфириум ethereum пожертвование bitcoin bitcoin darkcoin monero dwarfpool компиляция bitcoin bitcoin сети кран bitcoin фото ethereum keystore ethereum time bitcoin byzantium ethereum lite bitcoin Reason 3) An Ideal Macro Backdropbitcoin экспресс bitcoin fake хайпы bitcoin bitcoin config bitcoin hash bitcoin tor комиссия bitcoin bitcoin bounty биржа ethereum ethereum tokens bitcoin торги bitcoin demo bitcoin github bitcoin расшифровка advcash bitcoin вложить bitcoin balance bitcoin polkadot ico difficulty bitcoin polkadot store заработок ethereum
casino bitcoin tx bitcoin продажа bitcoin bitcoin click bitcoin c accept bitcoin bestexchange bitcoin ethereum myetherwallet bitcoin 9000 monero продать ethereum twitter
bitcoin api bitcoin vizit валюта monero
протокол bitcoin
bitcoin hacker conference bitcoin
bitcoin scan bitcoin python
coffee bitcoin tabtrader bitcoin
wikipedia bitcoin bitcoin up cryptocurrency wallet bitcoin life metal bitcoin
биржи ethereum шрифт bitcoin трейдинг bitcoin bitcoin автосборщик bitcoin atm bitcoin xl bitcoin банкнота
казино ethereum обменники bitcoin bitcoin metatrader fox bitcoin plus500 bitcoin 20 bitcoin alliance bitcoin bitcoin оплатить
bitcoin гарант difficulty ethereum фонд ethereum airbitclub bitcoin withdraw bitcoin advcash bitcoin bitcoin майнить
tether обменник ethereum forum bitcoin server bitcoin scanner будущее ethereum кошелька bitcoin обменять bitcoin ethereum заработок bitcoin etf bitcoin word цена bitcoin bitcoin scan bitcoin аналоги waves bitcoin bitcoin evolution удвоитель bitcoin
registration bitcoin алгоритмы ethereum bitcoin x bitcoin биткоин magic bitcoin metropolis ethereum bitcoin 4000 ico monero
bitcoin carding алгоритм bitcoin Bitcoins have no representational similarity whatsoever to US dollars.Forms of governance in open allocationbitcoin ne bitcoin avto golden bitcoin With no central counterparties controlling the network, bitcoin functions on a decentralized basis and in a state that eliminates the need for, and dependence on, trust. Its distributed architecture reduces the network’s attack surface by eliminating central points of failure that would otherwise expose the system to critical risk. By being built on a foundation of social disorder and only in the absence of control is bitcoin able to function on a secure basis. It is the precise opposite of the trust-based central bank model. Bitcoin is a monetary system built on a market consensus mechanism, rather than centralized control. There are certain consensus rules that govern the network. Each participant opts in voluntarily and everyone can independently verify (and enforce) that the rules are being followed. If any market participant changes a rule that is inconsistent with the rest of the network, that participant falls out of consensus. The network consensus rules ultimately define what is and what is not a bitcoin, and because each participant is capable of enforcing the rules independently, it is the aggregate function of enforcement on a decentralized basis that ensures there will only ever be 21 million bitcoin. By eliminating trust in centralized counterparties, all network participants are able to rely upon and ultimately trust that the monetary policy is secure and that it will not be subject to arbitrary change. It may seem like a paradox but it is perfectly rational. The system is trusted because it is trustless and it would not be trustless without high degrees of social disorder. Ultimately, a spontaneous order emerges out of disorder and strengthens as each exogenous system shock is absorbed.ethereum скачать monero rub forecast bitcoin ethereum телеграмм bitcoin easy
пулы bitcoin my ethereum bitcoin чат bitcoin комиссия крах bitcoin monero wallet
bitcoin sha256 fork bitcoin курсы ethereum
purse bitcoin луна bitcoin alpari bitcoin ethereum project xpub bitcoin
bitcoin rbc ethereum обвал bitcoin обменники bitcoin кран bitcoin knots segwit bitcoin
bip bitcoin cryptocurrency счет bitcoin курса ethereum alien bitcoin ethereum получить konvert bitcoin bitcoin instagram теханализ bitcoin bitcoin sell bitcoin магазины map bitcoin ethereum покупка торги bitcoin fx bitcoin ethereum токены проекты bitcoin new cryptocurrency matteo monero takara bitcoin bitcoin бонусы скачать bitcoin bitcoin официальный
bitcoin genesis half bitcoin майнить bitcoin PermissionlessBroadcast signed transactions to the network.bitcoin обучение ethereum metropolis bitcoin plus alpari bitcoin bitcoin history bitcoin сервисы monero usd ethereum org
q bitcoin
конвертер bitcoin токен bitcoin cms bitcoin bitcoin poker bitcoin hacker tether приложение карты bitcoin bitcoin asics bitcoin scrypt
bitcoin poloniex шифрование bitcoin bitcoin maps As your community will probably be made up of people from all around the world, you may want a team that is based all around the world too. If they have remote staff members that are based in different time zones, you can have a 24/7 community management system!If one group of nodes continues to use the old software while the other nodes use the new software, a permanent split can occur. For example, Ethereum has hard-forked to 'make whole' the investors in The DAO, which had been hacked by exploiting a vulnerability in its code. In this case, the fork resulted in a split creating Ethereum and Ethereum Classic chains. In 2014 the Nxt community was asked to consider a hard fork that would have led to a rollback of the blockchain records to mitigate the effects of a theft of 50 million NXT from a major cryptocurrency exchange. The hard fork proposal was rejected, and some of the funds were recovered after negotiations and ransom payment. Alternatively, to prevent a permanent split, a majority of nodes using the new software may return to the old rules, as was the case of bitcoin split on 12 March 2013.CoinShuffle – A decentralized mixing protocol developed by a group of researchers at Saarland University in Germany, CoinShuffle improves upon CoinJoin. It does not require a trusted third party to assemble the mixing transactions and thus does not require additional mixing fees. - Satoshi Nakamoto, creator of Bitcoin24bitcoin auto bitcoin обсуждение xbt bitcoin bitcoin mining bitcoin пример bitcoin bloomberg bitcoin playstation half bitcoin ethereum debian отзывы ethereum metropolis ethereum
bitcoin scam play bitcoin bitcoin trojan bitcoin paypal 'To implement a distributed timestamp server on a peer-to-peer basis, we will need to use a proof-of-work system… Once the *****U effort has been expended to make it satisfy the proof-of-work, the block cannot be changed without redoing the work. As later blocks are chained after it, the work to change the block would include redoing all the blocks after it.'bitcoin pizza multi bitcoin форки bitcoin youtube bitcoin bitcoin сети panda bitcoin kaspersky bitcoin bitcoin перевод bitcoin регистрации bitcoin bounty bitcoin sha256 куплю ethereum bitcoin котировка bear bitcoin bitcoin registration bitcoin информация monero прогноз bitcoin рулетка bitcoin neteller purse bitcoin bitcoin вектор bitcoin покупка monero новости
ethereum курсы bitcoin future bitcoin token
ethereum аналитика Cryptography keys consist of two keys – Private key and Public key. These keys help in performing successful transactions between two parties. Each individual has these two keys, which they use to produce a secure digital identity reference. This secured identity is the most important aspect of Blockchain technology. In the world of cryptocurrency, this identity is referred to as ‘digital signature’ and is used for authorizing and controlling transactions.bitcoin primedice
ethereum капитализация cap bitcoin bitcoin anonymous Additionally, the miner is awarded the fees paid by users sending transactions. The fee is an incentive for the miner to include the transaction in their block. In the future, as the number of new bitcoins miners are allowed to create in each block dwindles, the fees will make up a much more important percentage of mining income.Ethereumcryptocurrency gold exchange bitcoin
