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.
Now, let us see how these concepts work together. To record transactions, we need to put them in a database (like an Excel sheet).tether bootstrap equihash bitcoin ethereum pool chaindata ethereum tether курс bitcoin новости locate bitcoin казино ethereum
автосборщик bitcoin
ethereum контракт
bitcoin express bitcoin окупаемость nanopool ethereum bitcoin вложения bitcoin purse bitcoin dance bitcoin token bitcoin download elysium bitcoin bitcoin pay roboforex bitcoin
bitcoin knots сборщик bitcoin bitcoin betting покер bitcoin tether usdt bitcoin p2p make bitcoin bloomberg bitcoin bitcoin games bitcoin python
алгоритм bitcoin stats ethereum To highlight the difference in hashing power, at the time of writing, the total hashing rate of the bitcoin network is over 20,000 Terra Hashes per second, while litecoin is just 95,642 Mega Hashes per second.bitcoin работать price bitcoin android tether
bitcoin dark эфир ethereum mini bitcoin cardano cryptocurrency 2 bitcoin bitcoin ocean etoro bitcoin компания bitcoin кредит bitcoin зарегистрироваться bitcoin mindgate bitcoin bitcoin eu bitcoin перевод bitcoin pps ethereum coins uk bitcoin bitcoin лого cryptocurrency top casper ethereum market bitcoin bitcoin calc armory bitcoin
bitcoin club bitcoin change bitcoin заработок uk bitcoin bitcoin bloomberg wikipedia ethereum bitcoin algorithm ethereum rub серфинг bitcoin ethereum studio market bitcoin
cpuminer monero bitcoin steam кредит bitcoin установка bitcoin bitcoin путин команды bitcoin обновление ethereum multiply bitcoin лучшие bitcoin
bitcoin click мастернода bitcoin bitcoin ставки bitcoin котировка верификация tether криптовалют ethereum баланс bitcoin ethereum майнить monero xmr bonus bitcoin ethereum продам ethereum cryptocurrency bitcoin script bitcoin visa проверка bitcoin bitcoin стратегия bitcoin баланс instant bitcoin stake bitcoin bitcoin dynamics bitcoin pizza bitcoin collector бесплатный bitcoin gui monero global bitcoin скрипт bitcoin monero hardware bitcoin lucky twitter bitcoin ethereum купить collector bitcoin кликер bitcoin difficulty ethereum bitcoin аккаунт bitcoin blog краны monero electrum bitcoin баланс bitcoin
доходность ethereum fpga ethereum
cap bitcoin
бесплатный bitcoin bitcoin hardware pplns monero spin bitcoin case bitcoin bitcoin red ico ethereum робот bitcoin bitcoin выиграть криптовалюта tether bitcoin calculator nanopool ethereum monero криптовалюта
monero benchmark bitcoin video bitcoin information testnet ethereum bitcoin fpga ethereum описание ethereum raiden bitcoin доходность mini bitcoin bitcoin bow bitcoin poker cryptocurrency это ethereum получить bitcoin сети asics bitcoin bitcoin trend bitcoin make siiz bitcoin форк bitcoin ethereum кошелька ethereum miner
plasma ethereum валюта tether майнинга bitcoin ethereum получить инвестирование bitcoin карты bitcoin cryptocurrency market bitcoin оборудование лучшие bitcoin нода ethereum системе bitcoin bitcoin office The blockchain is transparent so one can track the data if they want toBanks are an example of what we would call a trusted third-party system. Banks and governments are third-party companies that we trust. To make it clearer, let’s see an example.multisig bitcoin bitcoin investment bitcoin change bitcoin farm xpub bitcoin bitcoin fields bitcoin форумы lavkalavka bitcoin app bitcoin trezor bitcoin обменники bitcoin
difficulty ethereum bitcoin кран bitcoin анализ average bitcoin monero logo best cryptocurrency ethereum заработать bitcoin bitcointalk сборщик bitcoin bitcoin сложность виджет bitcoin bitcoin weekly bitcoin alien ethereum casper bitcoin форекс миксер bitcoin
c bitcoin ethereum проекты bitcoin trust bitcoin traffic ethereum клиент bitcoin formula bloomberg bitcoin gadget bitcoin видео bitcoin ethereum erc20 bitcoin криптовалюта testnet ethereum 4pda tether pow bitcoin protocol bitcoin
bitcoin people
bitcoin казино monero asic bitcoin форк cryptocurrency bitcoin captcha bitcoin motherboard mt5 bitcoin 22 bitcoin bitcoin ecdsa bitcoin страна bitcoin cz ethereum продам bitcoin основатель vpn bitcoin логотип bitcoin Secondly, Litecoin transactions only take 2.5 minutes to arrive, which is much quicker than a bank transfer. It doesn’t matter if you want to send coins to someone on your street, or to someone on the other side of the world — it literally takes minutes for the funds to arrive!blog bitcoin master bitcoin bitcoin 20 crococoin bitcoin bitcoin сайты генераторы bitcoin
testnet bitcoin bitcoin central bitcoin journal rus bitcoin
bitcoin anonymous продаю bitcoin bitcoin котировки
bubble bitcoin разработчик bitcoin заработок ethereum партнерка bitcoin sec bitcoin 2016 bitcoin
second bitcoin Invest in the industry. This could become an option should companies such asNiceHash, Bitmain or Antminer ever become publicly traded.bitcoin step hashrate ethereum
sec bitcoin bitcoin email bitcoin список daemon monero ethereum валюта How does Ethereum work?cody-littlewood-and-im-the-founder-and-ceo-of-codelitt'In 2 years from now, I believe cryptocurrencies will be gaining legitimacy as a protocol for business transactions, micropayments, and overtaking Western Union as the preferred remittance tool. Regarding business transactions – you’ll see two paths: There will be financial businesses that use it for it’s no fee, nearly-instant ability to move any amount of money around, and there will be those that utilize it for its blockchain technology. Blockchain technology provides the largest benefit with trustless auditing, single source of truth, smart contracts, and color coins.'bitcoin kran In a pay-per-share (PPS) system, users are not rewarded based on how many blocks the pool actually finds, but rather on how many blocks the pool was expected to find given the amount of work done by its users. The pool pays a fixed amount of litecoins for each valid share its users submit, based on the mathematical laws of probability. The main advantage of this system is that users can enjoy steady payouts and minimal variance, and don't have to wait for blocks to be found and confirmed. The downside is that the pool operator has to take on the risk of bad luck, so running a PPS pool can be financially risky.Tensions between software developers and their employers have spilled out of Silicon Valley and into mainstream news. 'This engineer’s lament is a microcosm of a larger trend sweeping across the Peninsula' of San Francisco, reported Vanity Fair in August of 2018:green bitcoin ann monero ethereum torrent tether tools bitcoin dynamics zona bitcoin github bitcoin bitcoin global bitcoin автоматически логотип ethereum ethereum cpu bitcoin pizza bitcoin loans monero free attack bitcoin bitcoin spend easy bitcoin ethereum russia monero hardfork ethereum mine kurs bitcoin баланс bitcoin bitcoin trojan 999 bitcoin
bitcoin it bitcoin landing bitcoin zona billionaire bitcoin генераторы bitcoin bitcoin capitalization форк bitcoin monero пулы форк bitcoin ethereum хешрейт bitcoin cny How to Buy Litecoin via Exchanges?bitcoin office
Forcing risk taking on practically all individuals within an economic system is not natural nor is it fundamental to the functioning of an economy. It is the opposite and it is detrimental to the stability of the system as a whole. As an economic function, risk taking itself is productive, necessary, and inevitable. The unhealthy part is specifically when individuals are forced into taking risk as a byproduct of central banks manufacturing money to lose value, whether those taking risk are conscious of the cause and effect or not. Risk taking is productive when it is intentional, voluntary and undertaken in the pursuit of accumulating capital. While deciphering between productive investment and that which is induced by monetary inflation is inherently grey, you know it when you see it. Productive investment occurs naturally as market participants work to improve their own lives and the lives of those around them. The incentives to take risk in a free market already exist. There is nothing to be gained, and a lot to lose, through central bank intervention.bitcoin eu bitcoin trader
bitcoin клиент bitcoin history сайте bitcoin
bitcoin timer using spyware), while still enabling you to keep the flexibility of an onlinebitcoin hosting Before getting started, you will need special computer hardware to dedicate full-time to mining.bitcoin purchase
Daily fees (USD) paid to miners for a variety of top blockchains. Coinmetricsskrill bitcoin bitcoin блок bitcoin analysis bitcoin 10 monero стоимость electrum ethereum 33 bitcoin
bitcoin suisse bitcoin экспресс bitcoin conveyor bitcoin slots source bitcoin bitcoin roulette bitcoin ticker bitcoin мошенники bitcoin mining запросы bitcoin claymore monero обвал ethereum bitcoin 0 кости bitcoin bitcoin china bitcoin keys кредиты bitcoin explorer ethereum сложность ethereum bitcoin алматы usb tether bitcoin минфин сколько bitcoin bitcoin rus bitcoin token bitcoin auto новости ethereum ethereum os
bitcoin oil bitcoin пример
That’s the end of my 'What is Blockchain' guide! I hope you have understood everything I have explained, and I hope that you found it interesting!app bitcoin tails bitcoin цена ethereum bitcoin рулетка bitcoin комбайн 2x bitcoin bitcoin xt difficulty bitcoin bitcoin prominer прогноз ethereum course bitcoin bestchange bitcoin
биржи bitcoin ethereum blockchain bitcoin server
bitcoin fpga bitcoin сегодня bitcoin elena uk bitcoin bitcoin froggy
ethereum получить bitcoin cost 4 bitcoin
bitcoin презентация bitcoin flex connect bitcoin 'Block' refers to the fact that data and state is stored in sequential batches or 'blocks'. If you send ETH to someone else, the transaction data needs to be added to a block for it to be successful.форки ethereum создатель bitcoin компиляция bitcoin bitcoin knots bitcoin fan bitcoin investment торговля bitcoin tether bootstrap
1080 ethereum обмен tether secp256k1 ethereum token ethereum by bitcoin rus bitcoin bitcoin registration bitcoin роботы bitcoin download bitcoin проверка bitcoin check poloniex bitcoin the ethereum ropsten ethereum cryptocurrency arbitrage bitcoin чат finney ethereum bittrex bitcoin 22 bitcoin котировки bitcoin bitcoin nvidia
основатель ethereum bitcoin 3 The reason this works is because hashes in the Merkle tree propagate upward — if a malicious user attempts to swap a fake transaction into the bottom of a Merkle tree, this change will cause a change in the hash of the node above, which will change the hash of the node above that, and so on, until it eventually changes the root of the tree.half bitcoin bitfenix bitcoin bitcoin machine bitcoin trading nanopool ethereum bitcoin php bitcoin dance bitcoin перевод
bitcoin видео bitcoin обзор bitcoin количество часы bitcoin coinmarketcap bitcoin bitcoin краны life bitcoin лотереи bitcoin blogspot bitcoin символ bitcoin bitcoin экспресс explorer ethereum ethereum decred casinos bitcoin
bitcoin chains биржа bitcoin ethereum проблемы
bitcoin ферма bitcoin anonymous ethereum gas пузырь bitcoin bitcoin go bitcoin analytics bitcoin котировки bitcoin открыть майнинг ethereum фьючерсы bitcoin dance bitcoin transactions bitcoin monero bitcointalk автомат bitcoin статистика ethereum bitcoin generate
bitcoin legal monero пул bitcoin минфин Best Bitcoin mining hardware: Your top choices for choosing the best Bitcoin mining hardware for building the ultimate Bitcoin mining machine.lurkmore bitcoin bitcoin payza keystore ethereum bitcoin official форк bitcoin bitcoin faucet транзакции ethereum
bitcoin чат ethereum stats faucet ethereum q bitcoin луна bitcoin 1070 ethereum ethereum course mikrotik bitcoin neo cryptocurrency брокеры bitcoin bitcoin airbit bitcoin c bitcoin token
bitcoin loan reddit cryptocurrency bitcoin обменять loans bitcoin ферма bitcoin btc bitcoin bitcoin is шахта bitcoin bitcoin казахстан bitcoin отзывы bitcoin карта bitcoin code monero fr water bitcoin
bitcoin компания 100 bitcoin ethereum developer bitcoin advertising explorer ethereum
0 bitcoin bitcoin red blogspot bitcoin bitcoin google ethereum cgminer bitcoin bitcoin change добыча bitcoin agario bitcoin moneypolo bitcoin lottery bitcoin bitcoin knots bittorrent bitcoin 4pda tether bitcoin payza tether mining
bitcoin donate bitcoin usd бонусы bitcoin bitcoin официальный bitcoin betting bitcoin fpga bitcoin транзакция usb bitcoin project ethereum bitcoin банкомат bitcoin greenaddress
bitcoin mt4 sberbank bitcoin bitcoin 2016 bitcoin cgminer bitcoin nyse cpa bitcoin erc20 ethereum bloomberg bitcoin monero cryptonote
bitcoin scam bitcoin nvidia автомат bitcoin ethereum покупка bitcoin вклады bitcoin обналичить
тинькофф bitcoin Each Bitcoin exchange has different buying limits, which often varies depending on level of identity verification. At Coinbase, for example, regular users may only purchase up to $1,000 worth of bitcoins per day. Fully verified users, however, can buy up to $50,000 per day. Most exchanges offer a FAQ page online where the different levels of verification are explained.bitcoin journal are shared publicly, like an email address. When sending bitcoin to a counterparty, their public key can be considered the 'destination.'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.кошель bitcoin
cfd bitcoin bitcoin uk ethereum bitcoin prune bitcoin bitcoin code ethereum ферма bitcoin up bitcoin microsoft why cryptocurrency alipay bitcoin bitcoin hosting neo bitcoin alpari bitcoin андроид bitcoin ethereum алгоритмы сбербанк bitcoin maps bitcoin
bitcoin microsoft форекс bitcoin бесплатный bitcoin
майнер monero bitcoin видео bitcoin greenaddress asics bitcoin bitcoin buying
demo bitcoin bitcoin pay r bitcoin pirates bitcoin san bitcoin kinolix bitcoin gek monero
