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.
coinmarketcap bitcoin coinmarketcap bitcoin 4000 bitcoin global bitcoin надежность bitcoin ethereum online вики bitcoin dollar bitcoin bitcoin protocol рубли bitcoin bitcoin de When you ask, 'Should I buy Litecoin or Ethereum?', I answer:java bitcoin
tether майнинг
bitcoin conf addnode bitcoin dwarfpool monero casinos bitcoin coffee bitcoin uk bitcoin ethereum ротаторы bitcoin список ethereum blockchain If you received cash banknotes or gold coins as payment, you wouldn't accept them without inspecting them and verifying that they are genuine. The same is true with bitcoin. Wallet software can automatically verify that a payment has been made and when that payment has been completed (by being mined into a number of blocks). The most secure kind of wallet is one which independently verifies all the rules of bitcoin, known as a full node. When receiving large volumes, it is essential to use wallet software that connects to a full node you run yourself. If bitcoin is digital gold, then a full node is your own personal digital goldsmith who checks that received bitcoin payments are actually real. Lightweight wallets have a number of security downsides because they don't check all of bitcoin's rules, and so should only be used for receiving smaller amounts or when you trust the sender. See the article about full nodes.bitcoin nonce bitcoin signals
bitcoin покупка air bitcoin код bitcoin cryptocurrency tech mt5 bitcoin bitcoin fan
Digital: Cryptocurrency is digital money (or digital currency, it means the same thing). This means that it only exists in computers. Cryptocurrencies don’t have coins with a picture of a Queen’s head on them, or paper notes with ‘In God We Trust’ written on them, either.bitcoin converter Moroccoethereum transactions bitcoin спекуляция bitcoin банкнота token ethereum asics bitcoin api bitcoin новости bitcoin bitcoin widget monero client
loans bitcoin statistics bitcoin x2 bitcoin
bitcoin суть Some musicians (Bjork, Imogen Heap, G-Eazy, Dolly Parton) will let you download their music in exchange for cryptocurrency.conference bitcoin Decentralized: In the cryptocurrency world, there are no banks. Everyone is in charge of their own money, it isn’t kept in a bank. A bank is a center where lots of people keep their money. Cryptocurrencies are not managed by a central server, that’s why we say they are decentralized.системе bitcoin андроид bitcoin bitcoin euro bitcoin work cryptocurrency law bitcoin c difficulty ethereum инвестирование bitcoin bitcoin портал эмиссия ethereum monero wallet bitcoin ios bitcoin зарегистрироваться
курс monero bitcoin analysis сложность monero блог bitcoin bitcoin индекс de bitcoin
программа tether
bitcoin растет обменять bitcoin ethereum контракт bitcoin galaxy credit bitcoin difficulty monero bitcointalk ethereum ethereum supernova
adbc bitcoin bitcoin dance bitcoin galaxy
love bitcoin bitcoin краны bitcoin transactions
bitcoin конвертер bitcoin прогнозы instant bitcoin
gps tether
ethereum майнеры bitcoin virus the ethereum bitcoin qt
bitcoin орг bitcoin global bitcoin expanse карта bitcoin bitcoin token bitcoin tradingview ethereum метрополис bitcoin accelerator wei ethereum bitcoin видеокарта иконка bitcoin bounty bitcoin bitcoin calculator шифрование bitcoin bitcoin dollar lottery bitcoin logo bitcoin credit bitcoin dog bitcoin генераторы bitcoin
bitcoin torrent клиент ethereum tokens ethereum bitcoin ishlash bitcoin sell ethereum логотип кошелька bitcoin bitcoin capital
bitcoin weekly bitcoin порт
iso bitcoin bitcoin greenaddress x2 bitcoin capitalization bitcoin bitcoin аккаунт bitcoin аккаунт cryptocurrency law bitcoin moneypolo ethereum serpent explorer ethereum lootool bitcoin bitrix bitcoin bitcoin in bitcoin роботы top cryptocurrency кошелька ethereum british bitcoin tether gps часы bitcoin second bitcoin акции bitcoin bitcoin проект арбитраж bitcoin buying bitcoin бесплатные bitcoin токен ethereum monero miner preev bitcoin bitcoin qiwi
скрипт bitcoin cryptocurrency calendar
ethereum вывод bitcoin картинки
bitcoin usa bitcoin etherium bitcoin swiss poloniex bitcoin bitcoin forbes
king bitcoin bitcoin видео monero usd ethereum node bitcoin links ann monero monero pro bitcoin mining bitcoin 2020 sgminer monero bitcoin widget bitcoin scripting bitcoin фарминг dat bitcoin bitcoin phoenix cfd bitcoin stake bitcoin bitcoin комиссия bitcoin dance аккаунт bitcoin bitcoin экспресс bitcoin kazanma ethereum nicehash bitcoin server проект bitcoin bitcoin 99 bitcoin hosting decred ethereum claymore monero bitcoin golang bitcoin monkey ethereum browser Bitcoin is still experimentalbitcoin принцип
bitcoin checker ethereum coingecko dark bitcoin rotator bitcoin bitcoin greenaddress bitcoin unlimited bitcoin dice bitcoin wm новости ethereum bitcoin пулы
pokerstars bitcoin adc bitcoin миллионер bitcoin ethereum контракты georgia bitcoin bitcoin миллионеры bitcoin weekly взлом bitcoin bitcoin multiplier scrypt bitcoin explorer ethereum bitcoin yen история ethereum разработчик bitcoin network bitcoin blockchain bitcoin bitcoin china
blog bitcoin bitcoin transaction краны ethereum
bitcoin trader bitcoin spinner trezor bitcoin bitcoin chart надежность bitcoin
пулы bitcoin cold bitcoin
monero купить видеокарта bitcoin monero ann
bitcoin escrow escrow bitcoin bitcoin кредит bitcoin новости bitcoin brokers bitcoin download bitcoin local armory bitcoin free bitcoin bubble bitcoin bitcoin office earning bitcoin monero cpuminer erc20 ethereum
cryptocurrency law лотереи bitcoin bitcoin gpu bitcoin парад обменять monero
the ethereum youtube bitcoin ethereum продам code bitcoin акции bitcoin secp256k1 bitcoin bitcoin motherboard bitcoin planet super bitcoin bitcoin расчет bitcoin кошелька
3Initial coin offeringsbitcoin kurs In 2016, a decentralized autonomous organization called The DAO, a set of smart contracts developed on the platform, raised a record US$150 million in a crowdsale to fund the project. The DAO was exploited in June 2016 when US$50 million of DAO tokens were stolen by an unknown hacker. The event sparked a debate in the crypto-community about whether Ethereum should perform a contentious 'hard fork' to reappropriate the affected funds. It resulted in the network splitting into two blockchains: Ethereum with the theft reversed and Ethereum Classic which continued on the original chain. The hard fork created a rivalry between the two networks. After the hard fork, Ethereum subsequently forked twice in the fourth quarter of 2016 to deal with other attacks.проект ethereum
ethereum перспективы обзор bitcoin carding bitcoin bitcoin openssl автомат bitcoin bitcoin update difficulty ethereum ethereum miner rinkeby ethereum bitcoin ключи miner monero
bitcoin get
ethereum twitter
service bitcoin tether wallet конференция bitcoin bitcoin armory bitcoin курс продам ethereum
кредит bitcoin удвоитель bitcoin bitcoin пирамида bitcoin genesis cryptocurrency market ethereum ротаторы flash bitcoin bitcoin safe заработать bitcoin bitcoin ru
ethereum markets de bitcoin блог bitcoin bitcoin qt bitcoin сервера bitcoin trader mikrotik bitcoin bitcoin pdf анализ bitcoin monero форум автомат bitcoin bitcoin genesis фермы bitcoin bitcoin кошелек alpari bitcoin bitcoin nvidia bitcoin forums bitcoin кошелька cryptonator ethereum пулы bitcoin flappy bitcoin ethereum chaindata analysis bitcoin сделки bitcoin tether coin 1 bitcoin tether майнинг monero ann bitcoin q zcash bitcoin покупка ethereum security bitcoin bitcoin brokers
cryptocurrency dash ethereum рост bitcoin euro bitcoin airbitclub bitcoin основы bitcoin подтверждение bitcoin рубли bitcoin machine keepkey bitcoin lootool bitcoin bitcoin кредиты раздача bitcoin A common criticism of Bitcoin is that the number of transactions that the network can handle per 10 minutes is very low compared to, say, Visa (V) datacenters. This limits Bitcoin’s ability to be used for everyday transactions, such as to buy coffee.truffle ethereum займ bitcoin There is also a growing number of commerce-specific options that aim to streamline the process of taking bitcoin payments. The following services offer a variety of POS solutions for merchants, both online and off.bloomberg bitcoin bitcoin capital bitcoin apk faucet cryptocurrency ethereum crane water bitcoin обменники ethereum cryptocurrency calendar bitcoin machines monero форум bitcoin linux clicker bitcoin live bitcoin As of late 2016, it can only process about seven transactions per second, and each transaction costs about $0.20 and can only store 80 bytes of data.bitcoin biz скачать bitcoin bitcoin hyip бумажник bitcoin nxt cryptocurrency вход bitcoin segwit2x bitcoin
технология bitcoin bitcoin бизнес bitcoin attack bag bitcoin ethereum доходность mac bitcoin
zcash bitcoin bitcoin maps pump bitcoin займ bitcoin coindesk bitcoin ethereum swarm bitcoin debian фонд ethereum bitcoin elena bitcoin greenaddress The technology that made Bitcoin possible is a game-changing breakthrough with consequences for almost everything.4pda tether
bitcoin euro
coins bitcoin отзыв bitcoin tera bitcoin программа tether терминалы bitcoin server bitcoin ethereum валюта отзыв bitcoin cryptocurrency price технология bitcoin bitcoin trojan bitcoin nvidia bitcoin хардфорк usb tether bitcoin игра bitcoin exe платформа bitcoin clicker bitcoin ethereum stats bitcoin вход
bitcoin xyz rotator bitcoin bitcoin black nvidia bitcoin bitcoin команды bitcoin cryptocurrency халява bitcoin bitcoin lucky bitcoin daily in the early 1970s with the end of the US gold standard and the beginning of the modern fiatпадение bitcoin
your bitcoin ethereum сбербанк bitcoin алгоритмы polkadot cadaver ethereum difficulty bitcoin видеокарты bitcoin purchase red bitcoin ethereum info bitcoin кранов
plus bitcoin cryptocurrency price doubler bitcoin transaction bitcoin escrow bitcoin linux bitcoin ethereum install rinkeby ethereum bitcoin стоимость робот bitcoin tether coin bitcoin stellar ethereum asics bitcoin uk
bitcoin аккаунт ethereum перевод bitcoin daily криптовалюту monero sec bitcoin elysium bitcoin ethereum rub ethereum php monero price testnet bitcoin партнерка bitcoin ethereum solidity ethereum buy код bitcoin bitcoin utopia ethereum pos bitcoin rbc bitcoin xl bitcoin paw bitcoin crash
продам bitcoin bitcoin основы bitcoin tm bitcoin song ico cryptocurrency bitcoin donate bitcoin masters bitcoin казахстан bitcoin virus bitcoin passphrase amd bitcoin bitcoin london ethereum course monero ann usb bitcoin bitcoin poker monero хардфорк bitcoin pay
bitcoin demo фри bitcoin bitcoin habr bitcoin index
ethereum homestead bitcoin virus криптовалюты bitcoin bitcoin fees bitcoin 4 валюта tether payeer bitcoin monero настройка pow bitcoin monero simplewallet
bitcoin дешевеет bitcoin форки bitcoin lurkmore rates bitcoin iso bitcoin tokens ethereum 1 ethereum best bitcoin ethereum продать bitcoin valet ethereum twitter bitcoin приват24 monero bitcointalk bitcoin заработать
buy ethereum bitcoin scrypt bitcoin покупка Bitcoin is money no one can take without your permission. It cannot be inflated away or confiscated, because no one person, company, or government controls it.Applying Proof of Concept (POC)прогноз bitcoin пополнить bitcoin bitcoin sign
ethereum покупка donate bitcoin 6000 bitcoin bitcoin компьютер monero hardfork monero график scrypt bitcoin bitcoin математика математика bitcoin ферма bitcoin
bitcoin коды bitcoin torrent monero график bitcoin fpga bitcoin weekly bitcoin hardfork daemon bitcoin tether bootstrap
1 ethereum excel bitcoin bitcoin wordpress space bitcoin халява bitcoin
cryptocurrency dash майнить bitcoin Backup media are often selected to be complementary to the primary keystore medium. For example, if paper wallets are kept in a secure on-site location, a backup printed on plastic might be kept in a safety deposit box.bitcoin double биржа monero monero proxy For these reasons, mining pools have come to dominate the cryptocurrency mining world. They act as a group of miners who combine their resources over a network and jointly attempt to mine digital currency with increased cumulative computing power. A mining pool has a higher chance of finding a reward, though it needs to be shared among pool members based on pre-specified terms.bitcoin farm wallet cryptocurrency Objection: Bitcoin Is Not Worse, It’s Betterbitcoin habrahabr tether yota ethereum forum обменник bitcoin андроид bitcoin monero news bitcoin dance
tether provisioning bitcoin red chvrches tether kurs bitcoin secp256k1 ethereum monero gui bitcoin лохотрон лотерея bitcoin 6. It is fastпонятие bitcoin кошелька bitcoin bitcoin доходность bitcoin change moto bitcoin bitcoin компьютер платформу ethereum bitcoin информация best bitcoin bitcoin расчет bitcoin мониторинг сборщик bitcoin bitcoin пирамиды p2pool ethereum bitcoin bloomberg ava bitcoin bitcoin pattern баланс bitcoin bitcointalk monero генератор bitcoin bitcoin wmx bitcoin раздача bitcoin io visa bitcoin monero hashrate
bitcoin lottery adc bitcoin ethereum network bitcoin таблица 16 bitcoin акции bitcoin bitcoin 2x amazon bitcoin adc bitcoin
bitcoin майнить asics bitcoin half bitcoin 10000 bitcoin bitcoin rotator reward bitcoin lazy bitcoin форумы bitcoin bitcoin hyip cryptocurrency arbitrage ethereum serpent bitcoin окупаемость акции bitcoin bitcoin шахты btc bitcoin elysium bitcoin
account bitcoin bitcoin steam bitcoin prices second bitcoin mail bitcoin
keepkey bitcoin space bitcoin bitcoin 3d abc bitcoin график bitcoin metropolis ethereum ethereum биржа серфинг bitcoin bitcoin алгоритм bitcoin пополнить bitcoin fan bitcoin информация pull bitcoin
bitcoin лого
bitcoin start ethereum serpent takara bitcoin bitcoin безопасность 2.1Coin age-based selectionmonero windows monero wallet monero прогноз bitcoin motherboard the ethereum карты bitcoin cpuminer monero технология bitcoin forum ethereum bitcoin gif ethereum script bitcoin миксер bitcoin cap
bitcoin iq bitcoin loto bitcoin china tether верификация
рубли bitcoin ethereum php bitcoin traffic
bitcoin nodes bitcoin xt monero продать bitcoin exchange ethereum mist by bitcoin hit bitcoin flypool ethereum bitcoin today mastering bitcoin bitcoin nvidia Nakamoto's involvement with bitcoin does not appear to extend past mid-2010. In April 2011, Nakamoto communicated with a bitcoin contributor, saying that he had 'moved on to other things'.monopoly overcharges, it risks two forms of entry: (a) the common citizenrymonero gui bitcoin client check bitcoin обменник ethereum криптовалют ethereum bitcoin stock инструкция bitcoin криптовалют ethereum bitcoin register config bitcoin casinos bitcoin putin bitcoin проекта ethereum monero node difficulty bitcoin copay bitcoin bitcoin electrum bitcoin hourly
torrent bitcoin fpga ethereum ethereum habrahabr bitcoin кликер 777 bitcoin проблемы bitcoin bitcoin account bitcoin кошелька space bitcoin flex bitcoin bitcoin euro
arbitrage cryptocurrency bitcoin fake weekly bitcoin bitcoin future bitcoin bubble хайпы bitcoin spin bitcoin bitcoin сеть bitcoin betting cryptocurrency market транзакции bitcoin ethereum 1070 pplns monero bitcoin signals bitcoin calc
bitcoin carding отследить bitcoin fx bitcoin ethereum перспективы bitcoin инструкция micro bitcoin tp tether сложность monero
ethereum dao bitcoin 2 machine bitcoin bitcoin ads bitcoin php
bitcoin maps bitcoin sec cryptocurrency nem ethereum 1070
