Ethereum test network rinkeby

1. GPU mining

Hardware

algorithm is difficult to solve in memory. In order to make DAG suitable for memory, each GPU needs 1-2gb of memory. If you get an error prompt: error GPU mining. GPU memory fragmentation? It means you don't have enough memory. GPU mining software is based on OpenCL, amd GPU will be faster than NVIDIA GPU of the same level. ASIC and FPGA are relatively inefficient, so they are blocked. To get OpenCL for chip integration platform, try:
amd SDK OpenCL
NVIDIA CUDA OpenCL
Ubuntu Linux settings

for this quick guide, you will need Ubuntu 14.04 or 15.04 and fglrx image driver. You can also use NVIDIA drives and other platforms, but you have to find your own way to get an effective OpenCL installation, such as genoil's ethminer fork
if you are using 15.04, go to & quot; Software and updates 〉 extra drives & quot; Set to & quot; Use the video driver & quot; from fglrx for AMD graphics accelerator
if you are using 14.04, go to & quot; Software and updates 〉 extra drives & quot; Set to & quot; Use the video driver & quot; from fglrx for AMD graphics accelerator;. Unfortunately, for some people, this method may not work, because there is a known program error in Ubuntu 14.04.02 that will prevent you from switching to the exclusive graphics drive necessary for GPU mining
therefore, if you encounter this program error, go to & quot; "Software and update" update & quot; Select & quot; Pre release reliable update proposal & quot;. Then, back to & quot; Software and updates 〉 extra drives & quot; Set to & quot; Use the video driver & quot; from fglrx for AMD graphics accelerator;. After restarting, it's worth checking that the drive is now properly installed (for example, by going to & quot; Additional drives & quot;)
no matter what you do, if you are using 14.04.02, once installed, do not change the drive or drive configuration. For example, the use of aticonfig – initial (especially the - F, - force option) will & quot; Destruction & quot; Your settings. If you accidentally change the configuration, you will need to uninstall the drive, restart, install the drive again and restart.

2.

If you want to query the transaction records on the main network, you can use Etherscan. However, if you build your own private chain, how should you query the transaction records

the answer is that you need to listen to the logs on the chain, save them in the database, and then query them in the database. For example:

< pre t = "code" L = "Java" > varaddr = & quot& quot;< br />varfilter=web3.eth.filter({fromB lock:0 ,toBlock:' latest', address:addr });< br />filter.get(function(err,transactions){
transactions.forEach(function(tx){
vartxInfo=web3.eth.getTransaction(tx.transactionHash);
/ / at this time, the transaction information txinfo can be stored in the database
})< br />});

Web3. Eth. Filter() is used to monitor the log on the chain, and Web3. Eth. Gettransaction() is used to extract the information of the specified transaction. Once the transaction information is obtained, it can be stored in the database for query

recommend a practical introction, you can see: ethereum tutorial

3. Ethereum can be said to be a very successful currency in technology. In a short period of time, it has formed a trend of convergence. No matter in the technical level or in the market level, it has received global support, and the applications developed around it are emerging in an endless stream. At present, its price has been hovering at 3000 yuan for nearly half a month. I believe that with the progress of the bifurcation, its price is likely to exceed 4000 yuan by the end of the year. As the second largest market value of blockchain projects and bitcoin projects, its value is obviously likely to rise

Ethereum uses fog computing. The data processing and applications of fog computing are concentrated in the devices at the edge of the network, rather than almost all stored in the cloud, which is an extension concept of cloud computing, which is more in line with the spirit of decentralization of blockchain. If all the storage and operations still stay on the centralized server, then it will not be a real blockchain
recently, the hot "ethereal cat" on Ethereum network has led to the congestion of Ethereum network. The problem is that the TPS concurrency per second of Ethereum is too low. The emergence of ethereumfog with fog computing will break the embarrassing situation of Ethereum network congestion, and add powerful decentralized storage and additional computing power to the chain.

4. Ethereum can be said to be a very successful currency in technology. In a short period of time, it has formed a trend of convergence. No matter in the technical level or in the market level, it has received global support, and the applications developed around it are emerging in an endless stream. At present, its price has been hovering at 3000 yuan for nearly half a month. I believe that with the progress of the bifurcation, its price is likely to exceed 4000 yuan by the end of the year. As the second largest market value of blockchain projects and bitcoin projects, its value is obviously likely to rise

Ethereum uses fog computing. The data processing and applications of fog computing are concentrated in the devices at the edge of the network, rather than almost all stored in the cloud, which is an extension concept of cloud computing, which is more in line with the spirit of decentralization of blockchain. If all the storage and operations still stay on the centralized server, then it will not be a real blockchain
recently, the hot "ethereal cat" on Ethereum network has led to the congestion of Ethereum network. The problem is that the TPS concurrency per second of Ethereum is too low. The emergence of ethereumfog with fog computing will break the embarrassing situation of Ethereum network congestion, and add powerful decentralized storage and additional computing power to the chain

the concept of fog computing may be unfamiliar to many chain friends, but it is the most important aspect of ether fog to attract investors. In fact, I have heard about the concept of fog computing for a long time, and I have always thought that fog computing is the future development direction. When it comes to fog computing, we should start with cloud computing. In fact, the cloud computing we see now evolves from the cluster of independent servers, that is, from the original centralized independent servers to large server clusters, but in the final analysis, it is still a form of centralized computing. Compared with cloud computing, which is the evolution of centralized computing, fog computing is to share computing tasks with various computing power devices around us, and realize the evolution of decentralized and distributed computing, which coincides with the philosophy of blockchain itself.

5. I plan to start a series to talk about architecture. My previous experience is mainly in the area of Internet architecture. Recently, I am sorting out and analyzing the architecture of bitcoin, Ethereum and EOS, so I am going to write a series of articles to talk about the understanding of Internet architecture and blockchain architecture. It will be divided into four articles: 1. Internet proct architecture, 2. Bitcoin architecture analysis, 3. Ethereum architecture analysis, 4. EOS architecture analysis
there is no central server in Ethereum. Instead, there are many equal nodes connected by P2P protocol, which store all the data in many nodes. When a user initiates a transaction, the transaction will be broadcast out through P2P protocol. The miner node verifies, packages and further broadcasts the transaction to the whole network. After confirmation in the blockchain, the operation is considered to be unchangeable
in the articles on blockchain on the Internet, the two words distributed and decentralized are mentioned, sometimes slightly different, sometimes mixed. The author thinks that if we want to distinguish accurately, the distributed system emphasizes that multiple components work together by sending messages, and the decentralized system emphasizes that there is no central node to control the operation of the whole system. Therefore, we think that Ethereum is both decentralized and distributed, or running a decentralized program on a distributed platform.

6.

The postcode of Hefei city is 230000

the new administrative and cultural zone of Hefei is located in the southwest of the main urban area of Hefei, the provincial capital, with Jinzhai Road Viact in the East, Hefei high tech Instrial Development Zone in the West and Hefei Economic and Technological Development Zone in the south. With a planning area of 12.67 square kilometers, it is an important part of the main urban area in Hefei's "141" urban space development strategy. It is also a new political and economic center and commercial and cultural center of Hefei, the provincial capital, integrating the functions of administrative office, culture, ecation and sports, Finance and trade, tourism and vacation, residence and leisure

The common information of Hefei administrative district is as follows:

1. Area: About 6km southwest of the old city center

2. Area code: (+ 86) 0551

3. Administrative division code: 340100

4. License plate code: Wan a

extended information:

located in the main direction and heart of Hefei urban development sector, the new administrative and cultural zone is the only way to connect the main urban area, economic and Technological Development zone and university town. It is 20 minutes' drive from Hefei railway station, close to Hefei West Railway Station, and adjacent to Hefei Nanjing, Hefei Xuzhou, Hefei Wuhu expressways, It's only 10 minutes' drive from Hefei Luogang airport, and the airport and station are within the "living circle" of 20 minutes. It is not only the throat of the main urban area's westward and southward expansion, but also a beautiful window to reflect the image of modern Hefei City in the demonstration area of Wanjiang city belt's undertaking instrial transfer

China's postal code adopts a four level six digit structure. The first two digits indicate the province (municipality directly under the central government or autonomous region); The first three digits indicate the postal area; The first four digits represent counties (cities); The last two digits indicate the delivery office. Postcode is to realize the implementation of automatic mail sorting scheme, because the computer can not recognize Chinese, but can recognize numbers. Code each area, can quickly use the computer sorting, to write the more detailed the better

7. This is not very clear, because the research team in the central bank's digital currency is generally the relevant personnel of the central bank departments and their think tanks. As early as 2014, domestic banking institutions began to study digital currency
at present, the central bank's research on digital currency is still at an early stage, and it only plans to launch digital currency, but it is still far away from issuing digital currency. When the central bank studies digital currency, it may study the existing mainstream digital currencies such as bitcoin, Ruitai, dogcoin, etc.