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.
Hokkaidocryptocurrency bitcoin bitcoin аккаунт monero ann bitcoin daemon cryptocurrency faucet cranes bitcoin bitcoin spinner deep bitcoin ethereum transactions anomayzer bitcoin account bitcoin vk bitcoin bitcoin book ethereum tokens bitcoin бонусы ethereum стоимость ethereum сбербанк tether приложение icon bitcoin system bitcoin monero пулы monero биржи p2pool ethereum bitcoin nachrichten вебмани bitcoin bitcoin пожертвование dag ethereum fast bitcoin xpub bitcoin bitcoin count others. The millennial generation in particular has a distinct skepticismmonero форк
бесплатно bitcoin
bitcoin пулы получить bitcoin lavkalavka bitcoin bitcoin grant bitcoin up
rpc bitcoin зарабатывать bitcoin direct bitcoin hd7850 monero mooning bitcoin node bitcoin monero хардфорк bitcoin carding ethereum покупка create bitcoin автомат bitcoin bitcoin bbc bitcoin conference ethereum calc l bitcoin The moral hazards of management-controlled companies became increasingly obvious as the 1930s wore on. Management-controlled companies were run by executives which, despite not owning many shares, eventually achieved 'self-perpetuating positions of control' of policies, because they are able to manipulate the boards of directors through proxies and majority shareholder votes. These machinations sometimes created high levels of conflict. In the early 1940s, the idea emerged that this structural divide in the corporate world was being mimicked in the social and political worlds, with a distinct elite 'management class' emerging in society.bitcoin example символ bitcoin business bitcoin bitcoin change collector bitcoin ethereum gas bitcoin reindex ethereum контракты 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).перспективы bitcoin криптокошельки ethereum
ethereum конвертер bitcoin indonesia bitcoin система сайт bitcoin ethereum api ethereum icon bitcoin bcc pro bitcoin
bitcoin mempool metatrader bitcoin 6 Full Logo S-2.pngavatrade bitcoin куплю ethereum bitcoin koshelek ethereum com динамика ethereum bitcoin вложить ethereum акции
bitcoin reddit bitcoin бесплатные testnet ethereum bitcoin airbit пузырь bitcoin bitcoin сети курсы bitcoin oil bitcoin koshelek bitcoin майнинга bitcoin bitcoin de Scalabilityкомпиляция bitcoin reddit bitcoin приложения bitcoin криптовалюта ethereum
bitcoin putin алгоритмы bitcoin bitcoin рейтинг bitcoin компьютер nanopool ethereum bitcoin заработок яндекс bitcoin unconfirmed bitcoin nonce bitcoin bitcoin roll
forum bitcoin bitcoin aliens настройка ethereum сети ethereum bitcoin оборот amazon bitcoin bitcoin установка бесплатные bitcoin продать ethereum криптовалют ethereum lottery bitcoin bitcoin книги bitcoin обналичить bitcoin monkey ethereum проекты One would likely never come to this conclusion without first developing their own understanding of the following: i) that bitcoin is finitely scarce (how/why); ii) that bitcoin is valuable because it is scarce; and iii) that monetary networks tend to one medium. You may come to different conclusions, but this is the appropriate framework to consider when contemplating whether it is possible to copy (or out-compete) bitcoin rather than a framework based on any particular feature set. It’s also important to recognize that any individual’s conclusions, including your own or my own, has very little bearing in the equation. Instead, what matters is what the market consensus believes and what it converges on as the most credible long-term store of value.bistler bitcoin запросы bitcoin 9000 bitcoin bitcoin отслеживание ethereum developer перевести bitcoin rates bitcoin кости bitcoin avatrade bitcoin british bitcoin bitcoin gadget mastering bitcoin bitcoin луна bitcoin github bitcoin banks bitcoin cost статистика ethereum monero rur bitcoin mining bitcoin фермы пул ethereum bitcoin история дешевеет bitcoin
lootool bitcoin bitcoin official bitcoin eobot инструкция bitcoin escrow bitcoin обмен tether
bitcoin reserve bitcoin магазины microsoft bitcoin магазин bitcoin ethereum картинки
bitcoin халява перевести bitcoin bitcoin block
bitcoin greenaddress blogspot bitcoin bitcoin халява ethereum асик bitcoin обзор click bitcoin bitcoin trade пулы bitcoin bitcoin майнер видеокарта bitcoin bitcoin database bitcoin pdf ethereum farm
global bitcoin
film bitcoin
bitcoin cash bitcoin сбор bitcoin ann инвестиции bitcoin криптовалюта monero
кошелька ethereum ethereum crane отзыв bitcoin
bitcoin up blogspot bitcoin group bitcoin bitcoin hardfork cryptocurrency price top tether bitcoin flapper майнить monero ethereum frontier bitcoin cc coinbase ethereum bitcoin суть
bitcoin 3 The dichotomy between quantitative easing that central banks around the world are doing, and the quantitative tightening that Bitcoin just experienced with its third halving, makes for a great snapshot of the difference between scarcity or the lack thereof. Dollars, euro, yen, and other fiat currencies are in limitless abundance and their supply is growing quickly, while things like gold and silver and Bitcoin are inherently scarce.bitcoin проект mt4 bitcoin bitcoin airbit сервера bitcoin ethereum io портал bitcoin bitcoin mine
bitcoin hype bitcoin location bitcoin добыть bitcoin instaforex bitcoin tm
cryptocurrency reddit
bitcoin карты bitcoin advcash Privacy and security are concerns with traditional contracts. With so many intermediate parties involved, security can be compromised at any stage in the process. Security is maintained through cryptography, public key, and private keys when using smart contracts. Maintained in a decentralized system, the data is nearly impossible to modify. Smart contracts are digitally signed using private keys and can only be decoded by the public key shared by the parties involved.bitcoin ruble exmo bitcoin bitcoin click accepts bitcoin bitcoin оплатить bitcoin roulette system bitcoin bitcoin metatrader bitcoin оборудование loco bitcoin bitcoin blockstream ethereum supernova car bitcoin difficulty ethereum bitcoin crush bitcoin network проекты bitcoin ethereum bitcoin экспресс
bitcoin суть They have thousands of years of reliable history, and each precious metal has scarcity and inherent usefulness. They are all chemically unique, especially gold, and there are a very small number of precious metals that exist.bitcoin nodes bitcoin slots bitcoin украина cryptocurrency market bitcoin краны bitcoin торговля the ethereum txid bitcoin bitcoin scam куплю ethereum up bitcoin bitcoin ecdsa ethereum programming bitcoin change bitcoin project bitcoin register china bitcoin bitcoin win tether верификация
технология bitcoin зарабатывать ethereum freeman bitcoin
ethereum news bitcoin bcc bitcoin миллионеры microsoft bitcoin bitcoin цены
email bitcoin bitcoin криптовалюта Each time a block is produced and a miner is paid, new bitcoins come into existence. The computer which finds a lucky hash is paid a reward automatically by the network, in Bitcoin. This is called the coinbase reward. Like everyone else, miners must have a public key to receive these funds.bear bitcoin лото bitcoin alipay bitcoin
gadget bitcoin биржа bitcoin x2 bitcoin bitcoin symbol bitcoin майнить раздача bitcoin time bitcoin bitcoin history ethereum форум bitcoin investment search bitcoin ethereum io bitcoin биржи topfan bitcoin bitcoin clicks bitcoin markets bitcoin chart ethereum акции ethereum майнить bitcoin шахты crococoin bitcoin bitcoin стоимость bitcoin cudaminer куплю bitcoin
bitcoin instant forum ethereum
testnet bitcoin bitcoin алгоритм mac bitcoin an amount to someone else, but without information linking the transaction to anyone. This isпрогнозы bitcoin ethereum сайт bitcoin strategy blocks bitcoin s bitcoin
bitcoin location сбербанк bitcoin
bitcoin faucet bitcoin обменник polkadot ico ethereum casino ethereum info mini bitcoin стоимость bitcoin pps bitcoin
abi ethereum динамика ethereum blake bitcoin
bitcoin ledger flash bitcoin обмена bitcoin client bitcoin daemon monero bitcoin poloniex продам ethereum generator bitcoin config bitcoin fpga ethereum bitcoin котировки bitcoin slots bitcoin 2x fpga ethereum рост ethereum bitcoin keywords
bitcoin hardfork bitcoin мерчант fox bitcoin arbitrage bitcoin
monero benchmark exchange bitcoin bitcoin count api bitcoin bitcoin халява bitcoin халява ethereum ios bitcoin habrahabr bitcoin blog bitcoin chart bitcoin бесплатные покупка ethereum обзор bitcoin torrent bitcoin
simplewallet monero bitcoin development bitcoin рублей bitcoin получение создать bitcoin перевести bitcoin ethereum platform кликер bitcoin
vk bitcoin иконка bitcoin bitcoin blockchain bitcoin сервисы
bitcoin видеокарта config bitcoin будущее ethereum bitcoin 100 bitcoin trader разделение ethereum
ethereum настройка карты bitcoin bitcoin capital tether gps ethereum forum ethereum статистика bitcoin пицца bitcoin antminer bitcoin проект робот bitcoin bitcoin landing инструкция bitcoin bitcoin cgminer bitcoin euro
bitcoin исходники pos bitcoin китай bitcoin ethereum com bitcoin usd monster bitcoin ecdsa bitcoin bitcoin bux ethereum stratum monero пул bitcoin node system bitcoin ethereum casino shot bitcoin bitcoin bitminer bitcoin rpg ethereum регистрация ethereum crane stake bitcoin metal bitcoin Cryptocurrencies remove the power that banks and governments have over our lives. They give the power back to us. They also provide hope for all the people who have been left out of the modern banking system.bitcoin окупаемость get bitcoin bitcoin switzerland ethereum poloniex bitcoin 4096 monero новости bitcoin депозит moneypolo bitcoin hashrate ethereum bitcoin protocol bitcoin goldman ethereum ann bitcoin cap
s bitcoin
добыча bitcoin
bitcoin chart bitcoin girls bitcoin команды bitcoin rotators bitcoin kraken