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Chapter 250 Big Project

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    And these 3.5-inch aluminum alloy discs are the storage substrates of mechanical hard drives!  The working principle of a hard disk is actually no different from that of a tape recorder. They are both mounted on a carrier coated with magnetic paint, and the magnetic head discharge is used to change the arrangement direction of the magnetic paint to record information. Ò»?¿´Êéwww?w?¡¤1?¡¤cc It's just that the carriers used in tape recorders and video recorders are in the form of tapes, while hard disks with a larger amount of information and requiring faster reading and positioning use discs as magnetic carriers.  The earliest hard drive appeared in 1956.  "Limited by the limitations of materials, processing technology, electronic technology, and pneumatic theory, this hard drive is extremely huge. It is composed of fifty steel sheets with a diameter of 600 mm.  Each steel sheet is coated with magnetic material, and then the fifty discs are stacked together from the center. Each layer of discs has a separate magnetic head to read and write data.  Such a huge organization has only five trillion reserves!  After decades of research, scientific researchers finally designed a mature hard drive, which is the famous Winchester hard drive system in later generations. It includes a sealed hard drive casing, fixed and high-rotating disks, and slave disks.  The magnetic head moves radially outward from the center of the disk, and the magnetic head floats above the disk and does not directly contact the disk. This is composed of several technical principles.  ????In the middle, the self-floating technology of the magnetic head, the manufacturing technology of the disk with a highly smooth surface, the high-precision magnetic head technology, and the high-speed motor with stable and accurate positioning and fast response are the main technical difficulties in manufacturing hard disks.  Other technologies such as interfaces, data protection, shock protection, and data caching are relatively easy to implement.  Among these technical difficulties, the magnetic head and motor are the top priority.  Especially the magnetic head!  The width of the gap between the magnetic head and the disk information determines how much data a disk can store.  The sensitivity of the magnetic head determines the reliability of information reading.  Early magnetic heads used ferromagnetic materials, which had poor reliability and low data storage limit. A large 5.25-inch hard drive containing three to five disks had a total storage capacity of less than five megabytes.  Although the size is hundreds of times smaller than the original version, the storage limit has not been increased.  It wasn¡¯t until 1979 that IBM developed a thin-film magnetic head, and the read-write gap was narrowed to a level slightly thicker than the head wire, and the total storage capacity of the hard disk was increased.  A look at the book www?w?¡¤1k?a?nshu¡¤cc However, until 1981, the actual upper limit of available hard disk storage only reached 20 MB, and the price was as high as tens of thousands of dollars. Even for research with deep pockets  Institutions do not have the financial resources to purchase in large quantities. They can only be used as a computing center to save data and can be purchased in small quantities!  Since it is for personal use anyway, Guan Fei has no patience to follow the foreign technology and improve it bit by bit.  According to the manufacturing drawings he provided, the assembled production line directly skipped the thin film heads and produced MR heads.  However, he was not so crazy that he immediately took out a large-capacity hard drive with a storage capacity measured in g or even t. Instead, he chose AMR anisotropic magnetoresistive technology, using thin-film magnetic heads to write and strip-shaped magnetic materials to read.  method to increase hard drive capacity.  Under this technology, the magnetic head reads data by sensing changes in the magnetic field of the disk, so it is extremely sensitive.  And because the thin-film magnetic head is still used to write data, the technical implementation is very difficult.  On the contrary, the new read circuit uses fewer components, is easier to manufacture, and has lower processing costs than the original thin-film magnetic head.  Calculated based on the depreciation of the production line made in the base area and the wages of workers, the cost of a single hard drive is only one or two hundred yuan, which can be said to be cheap and high-quality.  The most difficult magnetic head is not a problem. Disk manufacturing, magnetic coating, interface, data protection, etc. are not difficult at all. Not only are they easily solved, but their performance is far superior to other similar products of the same period.  Through improvements, he can easily take out a 100-megabyte hard drive.  As a trainee in the early days, he asked him to start with the production of 80-megabit hard drives. After the quality control reached a certain level, he would gradually increase the production to produce 100-megabit, 150-megabit, 200-megabit and other series of hard drives.  The 80-megabyte hard drive alone has three times the capacity of hard drives currently available on the market, and the cost of single-megabyte data storage has been reduced to two yuan.  Compared with the retail price of IBM's 20-megabit hard drive, which is tens of thousands of dollars, the unit storage cost has been reduced by more than 20 times!  Guan Fei stayed at the hard drive factory for two days, answering the questions of the factory's technical staff about the problems encountered in production, and providing some improvement suggestions on the operating procedures and precautions during production.  These opinions are all key links that can significantly improve production capacity, production quality, and control yield rate through biological parabrain simulation. Although workers are not yet proficient in preliminary training, the actual production efficiency has obviously been greatly improved.  In the end, he returned home with a full load of the first batch of 500 80-megabyte hard drives produced in the factory, and then rushed to Xiamen without stopping.A factory fiber optic factory.  To read the book ¡¤1 k?a?nshu¡¤cc ¡­¡­ The birth of optical fiber originated from an experiment in the second half of the 19th century.  As we all know, light does not turn, it only moves in a straight line. As it spreads, the number of photons gradually decreases, and eventually disappears among other background clutter.  But in an experiment in 1870, British scientist Tyndall conducted an interesting experiment while giving a lecture on light reflection at the Royal Society.  He had a hole drilled into the side of a barrel filled with water, and then illuminated the barrel with light.  People were surprised to find that the light was actually wrapped in the curved water column. Instead of being diffused, it was distorted and emitted a bright light along with the flowing water.  From this, people discovered the light reflection effect, and based on this theory, a transparent material was used as the core and the outside was wrapped with an opaque shell to create an optical fiber, which was used as a medium for laser distortion transmission, so that the laser signal could be transmitted to  Information exchange can be achieved over several kilometers, tens of kilometers, or even hundreds of kilometers away.  It seems that manufacturing optical fibers is not difficult at all. Any transparent object can be used as the conductive material of optical fibers: quartz, glass fiber, or even plastic.  But in actual application, there are only three criteria for good or bad optical fiber: transmission loss, length and fiber diameter!  When light is transmitted over long distances, it will inevitably be refracted due to folding and turning. The lower the loss, the farther the light energy can be transmitted, the higher the bandwidth, the greater the amount of information it carries, and the intermediate  The fewer relay signal receiving and amplifying devices, the lower the laying cost.  The same goes for length.  The longer the length of a single optical fiber, the less intermediate equipment required and the lower the cost.  The fiber diameter is easier to understand.  In the middle of the optical fiber line, one optical fiber can be bundled, or there can be many optical fibers like ordinary cables.  The smaller the diameter, the greater the number of optical cables in a single optical fiber, the greater the channel volume, the greater the amount of information that can be transmitted instantly, and the greater the number of simultaneous communication users that can be supported.  With current technological capabilities, the transmission loss of a single optical fiber has been reduced to 0 per kilometer.  2db, which means that a 1oodb optical signal will have to be transmitted for 500 kilometers before it is completely attenuated.  The manufacturing length of a single optical fiber is two to three kilometers.  As for the diameter of the optical fiber, it is measured by the data transmission capacity of a single optical fiber. The current upper limit of optical fiber transmission is 140 megabits per second.  It can be seen that although the optical fiber loss rate is sufficient for practical use, the length is still very short, so even as an urban information trunk line, the cost is still extremely high.  Calculated based on the transmission length of 100 kilometers, a total of fifty sets of relay equipment are required. On average, the laying cost per kilometer is as high as five million US dollars.  Even in China, where labor costs are low, the unit cost of relay equipment is as high as tens or millions.  You must know that the cable laying in a city is often measured in thousands of kilometers!  If one set of relay equipment is prepared every two kilometers, a city's optical fiber network will require hundreds of sets of relay equipment, and the laying cost will be billions!  Such high cost means that even wealthy developed countries such as the United States, Britain, and Germany cannot afford full-fiber networks and can only use them as backbone lines.  Connected to various blocks and residential areas, traditional cables are still used as home connection lines.  The only ones that can afford it are those big banks with many branches. Because of the high transmission rate, they use it as a data transmission intermediary for ATM machines.  Guan Fei provided manufacturing drawings and produced this production line without spending too much effort on transmission loss. It only reduced the loss per kilometer to 0.  15db, others basically use existing technologies and materials, and focus on unit length.  With this production line, the drawing length of a single optical fiber reaches fifteen kilometers, and end-end splicing technology can be used to link multiple sections of optical fiber into long optical fiber lines that are tens or hundreds of kilometers long.  However, in order to reduce the bandwidth loss caused by transmission loss, it is best to keep the length of a single optical fiber at 50 kilometers.  With such an improvement, the number of relay equipment used in a thousand-kilometer all-fiber network has been reduced to about 20 sets.  Even if the cost of digging roads, burying pipelines and other projects does not decrease, the unit laying cost has dropped to tens of millions of dollars. It may still be a huge expense for developing countries, but for developed countries such as Europe and the United States, especially the Middle East oil  For resource-rich Arab countries, this is like free money!  ¡­ Guan Fei took advantage of the various research units to conduct reverse research on various parts of the parts and components. It took two weeks to inspect a few weeks of focusing companies.  Various problems encountered during the production processproblems, help them streamline their production processes, increase production capacity, and increase yield rates.  During this period, a series of key projects such as hard drives, optical fibers, program-controlled equipment chips, laser diodes, optical amplification equipment, etc. have achieved gratifying results.     All is ready except for the opportunity.  ¡­ ¡­ The Northern Theater Command is divided into three separate parts: the Military Command Department, the Administrative Department, and the Party Committee.  ??The administrative department and the party committee headquarters are both located in the third section of Renmin Avenue, facing the mountains to the west, facing the business district to the east, close to the New City First People's Hospital, and the research area to the north.  The two headquarters each have an office building group. There are two separate entrances and exits on the outside, but they are connected inside and are not separated.  The most important military headquarters is still located at the old military camp, which is in the hilly area about ten kilometers away from Longkang Town.  Most of the regular troops were stationed in Xingwei, Guogen, Gunong, Qingshuihe, Guigai, Muse and other places.  Among them, the Xingwei first-line defense system facing the Yading Army had the largest number of troops. A total of six brigades were deployed, spread out in echelons, and the defense front was 50 kilometers wide and 60 kilometers deep.  Facing the direction of the Wa mountainous area where the People's Party Central Committee is located, four brigades were also deployed.  There are only two brigades here at the headquarters.  Other domestic veterans and prisoners who have not yet been reorganized, as well as troops to be reorganized, are placed in the middle mountainous area, Tamengye area, using it as a training base, reorganizing and training at the same time, and protecting the future military industrial base.  Guan Fei¡¯s private research institute is located in the valley behind the military headquarters. Engineers have begun digging into the mountain wall. In the future, some laboratories will be further hidden in the heart of the mountain, improving safety and confidentiality.  Today, under the leadership of Guan Fei, a very important project is being carried out here. 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