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 serpent Polkadot’s core component is its relay chain that allows the interoperability of varying networks. It also allows for 'parachains,' or parallel blockchains with their own native tokens for specific use cases. bitcoin zone bitcoin allstars bitcoin scripting ethereum pow bitcoin com bitcoin machine майнер bitcoin
fork ethereum
bitcoin лохотрон 1000 bitcoin ethereum метрополис bitcoin okpay amazon bitcoin запросы bitcoin bitcoin принимаем daemon bitcoin bitcoin advertising ethereum coin bistler bitcoin bitcoin приложение андроид bitcoin bitcoin акции php bitcoin
clicker bitcoin coinder bitcoin игра ethereum установка bitcoin bitcoin автосерфинг краны monero monero пул lurk bitcoin график ethereum создать bitcoin red bitcoin faucet cryptocurrency mining cryptocurrency ethereum supernova ethereum биткоин фарминг bitcoin top cryptocurrency заработать monero платформу ethereum laundering bitcoin робот bitcoin boxbit bitcoin
bitcoin play bitcoin indonesia avto bitcoin трейдинг bitcoin This mechanism ensures that there will be no possibility of misuse due to an oversupply of XRP cryptocoins, and it will take many years before all the cryptocoins will be available.10 bitcoin ultimate bitcoin bitcoin payeer monero 1060
майнеры ethereum In the meantime, Bitcoin’s volatility can be managed by using appropriate position sizes relative to an investor’s level of knowledge and conviction in the asset, and relative to their personal financial situation and specific investment goals.bitcoin кошелька tether майнинг
bitcoin команды
комиссия bitcoin
monero pro Because bitcoin has inherent and emergent monetary properties, it is distinct from all other digital monies. While the supply of bitcoin remains fixed and finitely scarce, central banks will be forced to expand the monetary base in order to sustain the legacy system. Bitcoin will become a more and more attractive option, as more market participants figure out that future rounds of quantitative easing are not just a central bank tool but a necessary function to sustain the alternate and inferior option. Before bitcoin, everyone was forced to opt in to this system by default. Now that bitcoin exists, there is a viable alternative. Each time the Fed returns with more quantitative easing to sustain the credit system, more and more individuals will discover that the monetary properties of bitcoin are vastly superior to the legacy system, whether the dollar, euro or yen. Is A better than B? That is the test. In the global competition for money, bitcoin has inherent monetary properties that the fiat monetary system lacks. Ultimately, bitcoin is backed by something, and it’s the only thing that backs any money: the credibility of its monetary properties.Block ChainPrivate Keys: secures the unit of value, ensures ownership is independent from validation1: weiHow Much Does a Bitcoin Wallet Cost?book bitcoin bitcoin spinner bitcoin usa se*****256k1 ethereum подтверждение bitcoin bitcoin сбербанк bitcoin prosto bitcoin torrent капитализация ethereum remix ethereum instaforex bitcoin ethereum клиент работа bitcoin bitcoin genesis ethereum асик ethereum forks fasterclick bitcoin взлом bitcoin
bitcoin euro
аналитика ethereum bitcoin p2p 1 bitcoin metropolis ethereum bitcoin серфинг криптовалют ethereum скачать bitcoin ethereum описание bitcoin forex список bitcoin команды bitcoin bitcoin деньги робот bitcoin ethereum асик bitcoin eth cryptocurrency tech покер bitcoin торги bitcoin live bitcoin
ethereum pow 1 monero bitcoin окупаемость The up-front investment in purchasing 4 ASIC processors or 4 AMD Radeon graphic processing unitsbitcoin конвектор
стоимость bitcoin rocket bitcoin auto bitcoin bitcoin loan bitcoin blockchain bitcoin buying go ethereum bitcoin расчет parity ethereum дешевеет bitcoin locate bitcoin seed bitcoin партнерка bitcoin bitcoin sha256 bitcoin brokers ethereum android cran bitcoin запросы bitcoin monster bitcoin tether android курса ethereum bitcoin steam
шифрование bitcoin ethereum покупка logo ethereum bitcoin mmgp bitcoin проект magic bitcoin описание ethereum bitcoin maps
mercado bitcoin
swarm ethereum майнинга bitcoin
bitcoin account ethereum calculator monero nvidia bitcoin rotators connect bitcoin bitcoin безопасность bitcoin ocean bitcoin 100 ферма ethereum boom bitcoin зарегистрироваться bitcoin bitcoin poker monero pro bitcoin safe проекта ethereum bitcoin fund
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
bitcoin nasdaq The earliest alternative cryptocurrency of all, Namecoin, attempted to use a Bitcoin-like blockchain to provide a name registration system, where users can register their names in a public database alongside other data. The major cited use case is for a DNS system, mapping domain names like 'bitcoin.org' (or, in Namecoin's case, 'bitcoin.bit') to an IP address. Other use cases include email authentication and potentially more advanced reputation systems. Here is the basic contract to provide a Namecoin-like name registration system on Ethereum:торги bitcoin bitcoin express кран bitcoin bitcoin utopia bitcoin today токены ethereum сайты bitcoin wallets cryptocurrency 1080 ethereum monero address bitcoin buying platinum bitcoin ecdsa bitcoin film bitcoin иконка bitcoin ethereum farm cryptocurrency reddit download bitcoin bitcoin ira tether coin bitcoin мастернода space bitcoin bitcoin blue
js bitcoin bitcoin golden tether usd bitcoin создать usa bitcoin ethereum core ethereum btc
ethereum complexity client bitcoin ethereum txid краны monero bitcoin goldmine
poker bitcoin
free ethereum bitcoin stock bitcoin circle баланс bitcoin tether перевод цены bitcoin ethereum coingecko armory bitcoin
monero ico bitcoin расшифровка покупка ethereum bitcoin etherium bitcoin стратегия ethereum difficulty ethereum заработать alpha bitcoin mmm bitcoin ethereum картинки карты bitcoin ethereum course bitcoin регистрации bitcoin plus credit bitcoin bitcoin putin tether addon bitcoin презентация bitcoin pools ethereum покупка bitcoin цены
bitcoin auto трейдинг bitcoin greenaddress bitcoin майнер monero bitcoin compare Centralized organizations have let us down.Verification that the bitcoins are genuineобои bitcoin se*****256k1 bitcoin
blog bitcoin тинькофф bitcoin scrypt bitcoin credit bitcoin bitcoin телефон 2048 bitcoin
4 bitcoin bitcoin 5 click bitcoin new cryptocurrency
ethereum miner bitcoin timer bitcoin russia проект ethereum
bitcoin io bitcoin history
bitcoin баланс usd bitcoin The reason why the blockchain gets this property is that of the cryptographic hash function.This race to solve blockchain puzzles can require an intense amount of computer power and electricity. In practice, that means the miners might barely break even with the crypto they receive for validating transactions, after considering the costs of power and computing resources.bitcoin книга
Bitcoin exchanges such as Coinbase bring together market participants from around the world to buy and sell cryptocurrencies. These exchanges have been both increasingly popular (as Bitcoin's popularity itself has grown in recent years) and fraught with regulatory, legal and security challenges. With governments around the world viewing cryptocurrencies in various ways – as currency, as an asset class, or any number of other classifications – the regulations governing the buying and selling of bitcoins are complex and constantly shifting. Perhaps even more important for Bitcoin exchange participants than the threat of changing regulatory oversight, however, is that of theft and other criminal activity. While the Bitcoin network itself has largely been secure throughout its history, individual exchanges are not necessarily the same. Many thefts have targeted high-profile cryptocurrency exchanges, oftentimes resulting in the loss of millions of dollars worth of tokens. The most famous exchange theft is likely Mt. Gox, which dominated the Bitcoin transaction space up through 2014. Early in that year, the platform announced the probable theft of roughly 850,000 BTC worth close to $450 million at the time. Mt. Gox filed for bankruptcy and shuttered its doors; to this day, the majority of that stolen bounty (which would now be worth a total of about $8 billion) has not been recovered.bitcoin рухнул ютуб bitcoin auction bitcoin проверка bitcoin bitcoin value bitcoin grafik
zona bitcoin калькулятор bitcoin monero github trezor bitcoin
bitcoin play bitcoin capitalization system bitcoin panda bitcoin bitcoin payza ethereum картинки кредиты bitcoin ethereum investing bitcoin convert bitcoin farm котировка bitcoin bitmakler ethereum bitcoin ann transaction bitcoin ethereum crane асик ethereum
курс bitcoin ethereum прибыльность bitcoin tools bitcoin boom asic monero форк bitcoin платформе ethereum bitcoin capitalization bitcoin hesaplama tradingview bitcoin registration bitcoin ethereum casper
bitcoin traffic bitcoin окупаемость сеть ethereum описание ethereum карта bitcoin bitcoin aliexpress bitcoin grant bitcoin cran token ethereum bitcoin пожертвование bitcoin valet bitcoin смесители eth ethereum home bitcoin connect bitcoin king bitcoin bitcoin motherboard
видео bitcoin
генераторы bitcoin перспективы ethereum neo bitcoin
bitcoin обучение claim bitcoin bitcoin forbes bitcoin 4 bitcoin avalon bitcoin links map bitcoin ethereum php bitcoin tm capitalization bitcoin tether 2 график bitcoin mini bitcoin ropsten ethereum sec bitcoin monero форк dorks bitcoin get bitcoin bitcoin flex раздача bitcoin майнер ethereum tether bootstrap автомат bitcoin протокол bitcoin bitcoin bazar
вклады bitcoin ethereum форум ethereum addresses bitcoin кошелек платформа bitcoin converter bitcoin The biggest change compared to GPU that Field Programmable Gate Array has brought is the reduction in consumed power which decreased 5 times while giving a 30% boost in mining efficiency. This is the time when big players started joining the Bitcoin game.The now: ASICThe final (at least for now) method of mining Bitcoins is using the Application-Specific Integrated Circuit.протокол bitcoin сети ethereum bitcoin allstars bitcoin laundering торги bitcoin сша bitcoin ethereum exchange bitcoin алгоритм 1000 bitcoin
neo cryptocurrency обмен ethereum ethereum android bitcoin государство pool monero ethereum eth strategy bitcoin bitcoin prices bitcoin reindex bitcoin фарминг it bitcoin
теханализ bitcoin
bitcoin change часы bitcoin fire bitcoin bitcoin cache bitcoin best bitcoin center space bitcoin и bitcoin cran bitcoin котировки ethereum книга bitcoin accepts bitcoin ethereum myetherwallet As we discussed at the beginning of this report, Bitcoin is likely a disruptivecryptocurrency analytics preev bitcoin
майнер monero сборщик bitcoin bitcoin 9000 etoro bitcoin bitcoin обменники bitcoin wiki
взломать bitcoin сборщик bitcoin daily bitcoin bank bitcoin roulette bitcoin store bitcoin видеокарты bitcoin bitcoin airbit bitcoin favicon forex bitcoin coin bitcoin
microsoft bitcoin ethereum конвертер bitcoin slots конвектор bitcoin bitcoin хабрахабр bitcoin foto bitcoin сбор top bitcoin заработай bitcoin ethereum rotator bitcoin fun ethereum contracts ethereum php bitcoin qiwi сколько bitcoin bitcoin market bitcoin wmx ethereum com bitcoin уязвимости
ethereum стоимость avatrade bitcoin multiply bitcoin форк bitcoin bitcoin converter bitcoin автоматически получить bitcoin форк bitcoin api bitcoin bitcoin rbc exmo bitcoin tether wallet prune bitcoin bitcoin bestchange ethereum бутерин капитализация ethereum by bitcoin monero обменять ethereum создатель bitcoin цены avatrade bitcoin
flash bitcoin bear bitcoin bitcoin 20 okpay bitcoin fox bitcoin вклады bitcoin bitcoin презентация bitcoin bloomberg ethereum miners bitcoin ротатор bitcoin xpub ethereum mist ethereum forum python bitcoin bitcoin cranes
bitcoin рухнул ethereum видеокарты ethereum scan sberbank bitcoin
bitcoin checker bitcoin multiplier nicehash bitcoin bitcoin иконка bitcoin boom ethereum addresses bitcoin 30
microsoft bitcoin bitcoin fpga ethereum dao se*****256k1 ethereum bitcoin avalon bitcoin address алгоритм ethereum bitcoin plus
tether обменник coinder bitcoin bitcoin вложить ферма ethereum верификация tether криптовалюта ethereum monero blockchain bitcoin банкомат кошелька ethereum monero *****u tracker bitcoin cryptocurrency wallets bitcoin биткоин ethereum decred rbc bitcoin bitcoin antminer bitcoin 3 sec bitcoin падение ethereum bounty bitcoin bitcoin основы ethereum капитализация bitcoin форекс So-called paper wallets are an obsolete and unsafe method of storing bitcoin which should not be recommended to beginners. They simply store a single private/public keypair on paper. They promote address reuse and require unwieldy and complicated live OS system boots to be safe, they risk theft by printers, and typically rely on Javascript cryptography.bitcoin io ethereum видеокарты KEY TAKEAWAYSbitcoin hd bitcoin машины ethereum claymore фермы bitcoin earning bitcoin tracker bitcoin bitcoin dynamics отслеживание bitcoin
bitcoin kran cryptocurrency gold
cryptocurrency mining direct bitcoin hack bitcoin ethereum 2017 fpga bitcoin
bitcoin описание описание bitcoin ethereum api bitcoin click
bitcoin видеокарты
matteo monero flash bitcoin ethereum ann bitcoin payoneer bitcoin lottery asics bitcoin bitcoin conference china bitcoin bitcoin котировка bitcoin send эмиссия ethereum bitcoin vector bitcoin википедия hd7850 monero bitcoin cnbc
nodes bitcoin bitcoin department copay bitcoin bitcoin цена tether coin кредит bitcoin geth ethereum http bitcoin
ethereum обменники stratum ethereum bitcoin значок
advcash bitcoin bittorrent bitcoin сбербанк bitcoin 0 bitcoin
monero 1060 cranes bitcoin exchanges bitcoin ethereum alliance bitcoin генераторы daemon monero
cz bitcoin MEW (MyEtherWallet) - Web Wallet
