If you want to learn about the blockchain, the Bitcoin system is the first big knowledge module that we will definitely face. why is it like this? In yesterday’s sharing, we have mentioned that Bitcoin is the predecessor of the blockchain, and the blockchain is the later refinement of Bitcoin. The logical relationship between the two determines that Bitcoin is an inevitable guy; if everyone is When you first encounter Bitcoin, when you want to communicate with others, the first concept you face may be mining. So the question is coming? What does mining mean? What is the relationship between mining and Bitcoin? What is the principle of mining? and many more. These problems have troubled me for a long time in the process of learning blockchain. Below, let us take a look at them one by one. First, let us start with the relationship between Bitcoin and mining; Before starting this topic, let me ask a question: Have you ever wondered why every blockchain system has to issue its own digital currency? This is the ICO fever some time ago; this involves the fundamental role of the blockchain, which is: to realize the free circulation of social value on the blockchain (analogous to the fundamental role of the Internet: to realize the free circulation of information); For example, I can develop a car chain for cars, a house chain for houses, and a sow chain for sows; etc.; if an organization or individual has enough energy, I can also release a chain for the entire industry. It is estimated that only the central bank can do things; that cars, houses, sows... want to circulate freely on their respective chains, from under the name of A to under the name of B, or from under the name of C to under the name of D, must A measure of measurement is needed; this measure is accomplished by spending the corresponding digital currency; in other words, the digital currency issued by each chain serves as the general equivalent of the value circulation on the chain; make a realistic analogy: also It is the central currency such as RMB, U.S. dollar, Thai baht, British pound and so on used for transactions in our lives, which act as our shopping. Each chain can be compared to a country. Does each country have its own currency system? Thinking about it this way, is it clear why each chain issues digital currency, the purpose of which is to promote the smooth circulation of assets on the chain; As far as digital currency is concerned, for people who want to do things, it acts as a general equivalent of value circulation; for people who collect money, it is a tool for collecting money; Let's get to the main topic below: analyze the relationship between Bitcoin and mining; talk about the relationship between the two, we need to talk about the release mode of digital currency in the blockchain; From a general perspective: there are two main forms of digital currency on the blockchain release chain: one is like Bitcoin, which continuously consumes its own computing power through mining nodes, which is continuous mining. Meaning, in exchange for Bitcoin; because the Bitcoin system is completely open source, this set of open source codes contains the mining function. As long as one person understands the code, he can compile and deploy this set of codes and add it to the Bitcoin system. Go to the Bitcoin network, turn on the mining function, and your host machine will start mining; in the Bitcoin system, the mining difficulty of the entire network can be dynamically adjusted through its own algorithm to ensure that every 10 minutes, Bitcoin In the network, there will be a node that succeeds in mining; once someone succeeds in mining, the Bitcoin system will reward the person with a certain amount of Bitcoin. This amount is also controlled by an algorithm. This algorithm can be said: the first head In four years, each person who succeeds in mining will receive a reward of 25 bitcoins, which decays by half every four years; that is, 12.5 rewards for successful mining in the next four years, and 6.25 rewards for the next four years. By analogy; by about 2140, the blockchain is issued, a total of about 21 million bitcoins; Through the above explanation, everyone should understand the relationship between mining and Bitcoin. This relationship is: mining is the only way for the Bitcoin system to issue its own digital currency, which is the only way for Bitcoin. The Bitcoin system uses mining to complete the issuance of its own digital currency; the process of issuing digital currency is a process in which various miners compete for mining. In every 10 minutes, to see who digs into the mine first, a certain amount of Bitcoin will be rewarded. This reward process is the process of Bitcoin issuance; each mining node is driven by profit and constantly thinks of ways to be able to Faster mining, which has spawned a variety of mining pool nodes on the market; Just now we said that there are two main forms of digital currency issuance; Bitcoin is one; the other, I take domestic NEO as an example; NEO’s issuance model is: when the system is created, one-time in In the genesis block, write 100 million NEO; with the help of ICO, users can directly use RMB to subscribe and hold; this model is somewhat similar to the issuance of RMB by the central bank; while the issuance model of Bitcoin is very similar to that of gold rush; In the sharing just now, we kept mentioning mining, but what about the low mining in Bitcoin? In fact, mining is a visual expression in the Bitcoin system; the real name behind it is the POW algorithm, which is the proof-of-work algorithm; the proof-of-work comes from economics; in 1993, it was created by two economies. One of the strategies proposed by scientists is to prevent the abuse of services or resources, and to adopt an economic strategy of effective blocking; This POW has been widely used before Bitcoin; the more famous one is the anti-spam system of Google Mail; how does Google use it? Google does this: it requires that every other server that sends emails to the google mail server must complete a certain amount of calculation work; this calculation may take 2 to 3 seconds for the other side's service thread; 2 to 3 seconds, if it is A person sending emails is completely tolerable; if the other party is a script program that sends spam, he can't bear it at all. The email script needs to send out thousands or hundreds of emails per second; How is it used in the Bitcoin system? When Satoshi Nakamoto designed and implemented the Bitcoin system, he hoped to complete Bitcoin issuance every 10 minutes. Since there are tens of thousands of nodes in the Bitcoin network, who should issue the coins to? According to the proof-of-work strategy, that is, the idea of ​​the POW algorithm, Satoshi Nakamoto posed a problem for each node in the Bitcoin system. Let’s take a look at the screenshot below the voice. This is the data structure of a block header. , Everyone, please pay attention, there is a Nonce field in it; Satoshi Nakamoto’s problem is: under the premise that the value of other fields remains unchanged, by constantly adjusting the value of Nonce, the structure value of BlockHeader is calculated as a Hash, and it is required to find a Nonce. Value so that the calculated hash value is less than or greater than a certain fixed value. This fixed value is marked by Bits in the BlockHeader structure; Since the hash algorithm is an irreversible algorithm, it is impossible to derive the original text through a specific hash value; in this way, each node can only use an exhaustive method, that is, starting from 1, 2 3 4 5. Continue to try later; in this process, the CPU calculation speed of each node is tested. The calculation is fast, and the Nonce value will be obtained soon. Then he puts the Nonce value in the structure and passes through the P2P network. Broadcast out; after each system node receives it and finds that the Nonce value is legal and can meet the requirements, it is considered successful; for those nodes that have counted half of the time, they find that someone has already calculated it, so they will give up this exhaustion.了; Then start to find the Nonce value of the next block header through exhaustive methods; In this way, everyone will understand that the so-called mining is the process of the computer constantly looking for the Nonce value and calculating the Hash value through exhaustive methods; whoever finds it first will succeed in mining.
Small computer system interface (SCSI) is an independent processor standard for system level interfaces between computers and intelligent devices (hard disks, floppy drives, optical drives, printers, scanners, etc.). SCSI is an intelligent universal interface standard.
In addition to SCSI, IDE is also a very common interface. From the point of view of ease of use, IDE is more suitable for ordinary users. In addition, personal computer users not only need to configure a few peripherals, but also do not require high speed. Therefore, it is more appropriate to choose IDE interface. In addition, IDE also has the characteristics of high performance price ratio and wide application. Although the SCSI interface has many incomparable characteristics, the price of the interface and its peripherals is too expensive to be borne by ordinary users, which determines the limitation of its actual use range. SCSI Solder Type Section ShenZhen Antenk Electronics Co,Ltd , https://www.pcbsocket.com
1. The working mode of IDE requires the whole process participation of CPU. When the CPU reads and writes data, it can't perform other operations. In this case, in the multitask operating system of Windows 95 / NT, the system reaction will be greatly slowed down. The SCSI interface controls the data reading and writing operation completely through the independent high-speed SCSI card, so the CPU does not have to waste time to wait, which obviously can improve the overall performance of the system. However, IDE interface has also made great improvements to improve this problem. DMA mode can be used instead of PIO mode to read and write data. DMA channel is responsible for data exchange, which greatly reduces the CPU consumption. However, comparing the CPU utilization of SCSI and IDE, we can find that SCSI still has considerable advantages.
2. The scalability of SCSI is larger than that of IDE. Generally, each ide system can have two IDE channels, with a total of four IDE devices. The SCSI interface can connect 7-15 devices, much more than IDE, and the cable connected is far longer than ide.
3. Although the price of SCSI device is higher, compared with IDE, the performance of SCSI is more stable, durable and reliable.