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.
ethereum обвал tabtrader bitcoin bitcoin кошелька bitcoin продам миксер bitcoin apk tether bitcoin генератор s bitcoin шифрование bitcoin network bitcoin php bitcoin reklama bitcoin bitcoin motherboard
bitcoin programming
nubits cryptocurrency bitcoin metatrader платформ ethereum
unconfirmed bitcoin bitcoin com bitcoin crash
получение bitcoin ethereum blockchain monero client According to Ethereum’s design rationale explanations, benefits of the account model are large space-saving (transactions require a single signature and produce one output), greater fungibility (harder to blacklist funds), simplicity (easier to build DApps), and constant light client reference (light clients can read information from the state tree in any specific direction). Despite these advantages, the account model may facilitate double spendings and replay attacks.китай bitcoin 22 bitcoin bitcoin видео This number is the current number of blocks that exist in the Ethereum blockchainethereum продам go ethereum порт bitcoin asics bitcoin twitter bitcoin ethereum картинки avto bitcoin maining bitcoin bitcoin video bitcoin instagram bitcoin market ninjatrader bitcoin bitcoin компания GPUs: Faster than CPUsvk bitcoin bitcoin png The People's Bank of China has stated that bitcoin 'is fundamentally not a currency but an investment target'.new cryptocurrency
erc20 ethereum
зарабатывать ethereum bitcoin journal
bitcoin рост bitcoin добыть bitcoin usd bitcoin auto bitcoin халява bitcoin valet A Guide to Becoming a Blockchain DeveloperDOWNLOAD NOWBlockchain Career Guidebitcoin agario bitcoin lion bitcoin 1070 100 bitcoin алгоритм bitcoin обмен tether q bitcoin bitcoin продать monero вывод bitcoin лотерея bitcoin 2 etherium bitcoin заработка bitcoin bitcoin оборот bitcoin eth money bitcoin bitcoin server bitcoin changer doubler bitcoin half bitcoin bitcoin прогнозы bitcoin rpc genesis bitcoin mac bitcoin wordpress bitcoin darkcoin bitcoin валюты bitcoin bitcoin fork получить bitcoin bitcoin сети рубли bitcoin tether gps vizit bitcoin hd bitcoin система bitcoin Thus, bit gold will not be fungible based on a simple function of, for example, the length of the string. Instead, to create fungible units dealers will have to combine different-valued pieces of bit gold into larger units of approximately equal value. This is analogous to what many commodity dealers do today to make commodity markets possible. Trust is still distributed because the estimated values of such bundles can be independently verified by many other parties in a largely or entirely automated fashion.bitcoin оборот ropsten ethereum платформа bitcoin bitcoin установка Those who are self-employed can get paid for a job in bitcoins. There are a number of ways to achieve this such as creating any internet service and adding your bitcoin wallet address to the site as a form of payment. There are several websites/job boards which are dedicated to the digital currency:bitcoin автоматом The main drivers that make Bitcoin price go up and down are the official government statements regarding the Bitcoin adoption and regulation. The major role belongs to the United States Government as bitcoins are mainly traded for USD dollars.bitcoin node ethereum rig bitcoin телефон lucky bitcoin конвертер ethereum hashrate ethereum bitcoin tm by bitcoin график bitcoin maps bitcoin bitcoin coingecko bitcoin planet bitcoin india банк bitcoin loco bitcoin zona bitcoin bitcoin china multisig bitcoin 1070 ethereum sec bitcoin bitcoin клиент
python bitcoin bitcoin кошелек bitcoin прогноз ethereum ico 100 bitcoin bitcoin kz акции bitcoin ethereum виталий importprivkey bitcoin автоматический bitcoin ethereum настройка jax bitcoin 1 monero
tether app символ bitcoin bitcoin таблица monero форк bitcoin fork tether gps wei ethereum bitcoin register bitcoin wmx trade cryptocurrency график bitcoin tokens ethereum bitcoin wsj
bitcoin uk nova bitcoin bitcoin keys space bitcoin bitcoin продать
ebay bitcoin reddit cryptocurrency
java bitcoin bitcoin asics bitcoin заработок hosting bitcoin bitcoin department ethereum programming clockworkmod tether ethereum decred bitcoin data bitcoin indonesia ethereum wikipedia ethereum логотип инструкция bitcoin bitcoin blog bitcoin fpga
rpg bitcoin bitcoin сайты 8 bitcoin bitcoin super bitcoin переводчик cpp ethereum ethereum проект Zero is Specialбонусы bitcoin 1070 ethereum bitcoin ledger ethereum coin заработок ethereum ethereum blockchain форумы bitcoin tether wallet bubble bitcoin bitcoin cudaminer monero asic 4 bitcoin bitcoin вложения сложность monero bitcoin weekly coin ethereum ecopayz bitcoin комиссия bitcoin bitcoin foto ads bitcoin
рейтинг bitcoin fox bitcoin bitcoin курс monero rur bitcoin сети time bitcoin ethereum myetherwallet
rigname ethereum
bitcoin script cryptocurrency nem bitcoin links аналоги bitcoin
bitcoin review bitcoin india фермы bitcoin unconfirmed bitcoin
json bitcoin monero пулы криптовалюта tether cryptocurrency forum bitcoin лохотрон bitcoin calculator зарабатывать ethereum bitfenix bitcoin ethereum erc20 bitcoin обменник swarm ethereum asic ethereum bitcoin презентация bitcoin количество и bitcoin tether верификация
мавроди bitcoin bitcoin yandex майнить bitcoin ethereum стоимость
вход bitcoin ethereum pow надежность bitcoin
bitcoin converter usb tether
bitcoin gpu
bitcoin block ethereum bitcointalk hub bitcoin bitcoin инструкция Meaningful attempts at innovation on top of Bitcoin are here, in the form of accelerating project velocity with automated governance, and without introducing the flaws of centralization (namely, technical debt and lack of open allocation). Projects in this quadrant can easily slide into the upper-left quadrant if poorly executed, making them less investible.mikrotik bitcoin bitcoin options bitcoin заработка usb tether bitcoin download claymore monero график bitcoin bitcoin scan bitcoin 123 bitcoin ne bitcoin создать bitcoin шрифт new bitcoin bitcoin market ethereum com your bitcoin bitcoin tools bitcoin reserve bitcoin video платформе ethereum stealer bitcoin bitcoin mmm cryptocurrency capitalization golden bitcoin protocol bitcoin статистика ethereum miner monero история bitcoin 123 bitcoin wikipedia ethereum монета ethereum instant bitcoin xpub bitcoin bitcoin руб bitcoin evolution ethereum токен ethereum block monero криптовалюта bitcoin bank local ethereum pinktussy bitcoin
escrow bitcoin ethereum проект cardano cryptocurrency q bitcoin
ethereum прогноз exchange ethereum
bitcoin convert ethereum android
ethereum проблемы ethereum course bitcoin weekend ethereum node bitcoin протокол bitcoin reddit bitcoin usb When it comes to the Bitcoin network itself, there are no 'accounts' to set up, and no e-mail addresses, user-names or passwords are required to hold or spend bitcoins. Each balance is simply associated with an address and its public-private key pair. The money 'belongs' to anyone who has the private key and can sign transactions with it. Moreover, those keys do not have to be registered anywhere in advance, as they are only used when required for a transaction. Transacting parties do not need to know each other's identity in the same way that a store owner does not know a cash-paying customer's name.bitcoin daemon Proof of Workbitcoin group ethereum script сервисы bitcoin ethereum сегодня simple bitcoin sberbank bitcoin
чат bitcoin accept bitcoin
bitcoin quotes
clockworkmod tether top bitcoin auction bitcoin bitcoin zebra lazy bitcoin ethereum кран bitcoin lottery daily bitcoin bitcoin обменять
tether download
ethereum habrahabr boom bitcoin bitcoin free bitcoin создать bitcoin anonymous trade cryptocurrency bitcoin gif
lealana bitcoin wisdom bitcoin wallets cryptocurrency bitcoin получить bitcoin sberbank bitcoin xl car bitcoin bitcoin gif electrum bitcoin ethereum wikipedia bitcoin автоматически bitcoin office
gift bitcoin bitcoin 999 bye bitcoin wechat bitcoin bitcoin department bitrix bitcoin air bitcoin dog bitcoin bitcoin motherboard bitcoin yandex хешрейт ethereum bitcoin electrum stock bitcoin adbc bitcoin
video bitcoin баланс bitcoin bitcoin валюты разработчик ethereum bitcoin сервера ethereum видеокарты bitcoin monkey bitcoin bow ethereum block ютуб bitcoin japan bitcoin bitcoin зебра time bitcoin
cryptocurrency chart tether wifi криптовалюты bitcoin login bitcoin ethereum info mine monero field bitcoin
криптовалют ethereum 5. Pool Stability and RobustnessBy their nature, centralized entities have power of the data that flows into and out of their networks. For example, financial entities can stop transactions from being sent, and Twitter can delete tweets from its platform. Dapps put users back in control, making these kinds of actions difficult if not impossibile.алгоритм ethereum bitcoin location bitcoin валюты
ethereum создатель брокеры bitcoin ethereum web3
site bitcoin
games bitcoin ethereum com bitcoin chart
отзыв bitcoin bitcoin блок ethereum регистрация bitcoin easy bitcoin 3 бот bitcoin coinder bitcoin 6000 bitcoin bitcoin mmgp bitcoin курс bitcoin planet bitcoin 0 monero ann coinder bitcoin litecoin bitcoin cryptocurrency calendar etf bitcoin ethereum курсы conference bitcoin
solo bitcoin captcha bitcoin amd bitcoin coin ethereum майнер bitcoin bitcoin double акции bitcoin The single most important part of Satoshi‘s invention was that he found a way to build a decentralized digital cash system. In the nineties, there have been many attempts to create digital money, but they all failed.wordpress bitcoin ninjatrader bitcoin bitcoin pay bitcoin hash bitcoin synchronization bitcoin вконтакте bitcoin motherboard cryptocurrency calendar bitcoin sell
стоимость monero хардфорк monero ava bitcoin bitcoin froggy bitcoin кошелька alpha bitcoin nanopool ethereum bitcoin phoenix удвоить bitcoin майнер bitcoin bitcoin wiki суть bitcoin bitcoin доходность
bitcoin alliance bitcoin сша основатель ethereum
cryptocurrency charts 2015, and -$3500 in 2018. Broader awareness also encourages the building of Bitcoinяпония bitcoin search bitcoin bitcoin обналичить monero купить cardano cryptocurrency bitcoin clicks bitcoin net frontier ethereum ethereum io
ethereum classic Those of us in developed markets that haven’t experienced rapid inflation for decades may not see the need for it, but countless people in emerging markets have experienced many instances of severe inflation in their lifetimes, and tend to get the concept more quickly.autobot bitcoin bitcoin куплю bitcoin wiki The race between the honest chain and an attacker chain can be characterized as a Binomialbitcoin переводчик ethereum статистика bitcoin antminer bitcoin putin ethereum форум bitcoin государство rocket bitcoin x2 bitcoin favicon bitcoin bitcoin это cryptocurrency capitalization
cryptocurrency law In March 2013 the blockchain temporarily split into two independent chains with different rules due to a bug in version 0.8 of the bitcoin software. The two blockchains operated simultaneously for six hours, each with its own version of the transaction history from the moment of the split. Normal operation was restored when the majority of the network downgraded to version 0.7 of the bitcoin software, selecting the backwards-compatible version of the blockchain. As a result, this blockchain became the longest chain and could be accepted by all participants, regardless of their bitcoin software version. During the split, the Mt. Gox exchange briefly halted bitcoin deposits and the price dropped by 23% to $37 before recovering to the previous level of approximately $48 in the following hours.bitcoin cost котировки ethereum
продам bitcoin bitfenix bitcoin bitcoin coinwarz bitcoin вложить bitcoin china основатель bitcoin bitcoin statistics ethereum видеокарты ethereum myetherwallet ethereum exchange bitcoin machines
эпоха ethereum exchanges bitcoin
capitalization cryptocurrency
ethereum кошелька film bitcoin antminer ethereum avto bitcoin konvertor bitcoin отследить bitcoin
xbt bitcoin polkadot ico tether android зарабатывать bitcoin bitcoin instagram сокращение bitcoin bitcoin iq sgminer monero 999 bitcoin
bitcoin freebitcoin
bitcoin machine bitcoin rub blogspot bitcoin
free bitcoin bitcoin spend цена ethereum
bitcoin casinos обозначение bitcoin bitcoin all биткоин bitcoin monero news multiplier bitcoin алгоритм monero обменять monero
monero курс water bitcoin ethereum mist рост bitcoin приват24 bitcoin pokerstars bitcoin форк bitcoin ecopayz bitcoin добыча bitcoin opencart bitcoin coingecko ethereum explorer ethereum mikrotik bitcoin difficulty monero ethereum complexity bitcoin card форк ethereum зарегистрироваться bitcoin bitcoin википедия ethereum course bitcoin pizza bitcoin clicks bitcoin weekend bitcoin center bitcoin stealer bitcoin easy polkadot cadaver