1. magnetic storage technology
Magnetic storage system, especially hard disk storage system, is the most important storage equipment in various computer systems today, and occupies a dominant position in information storage technology.
(1) Magnetic storage media Magnetic media are all made by plating a magnetic film on a strip-shaped or disc-shaped tape base. Commonly used magnetic storage media include computer tapes, computer disks (floppy disks, hard disks), tape recorders, video recorders, etc.
(2) Characteristics of magnetic storage
Magnetic energy stores all information that can be converted into electrical signals, such as sound, image and thermo-mechanical vibration. It has the following characteristics: storage frequency bandwidth, which can store signals from DC to more than 2 MHz; Information can be stored on magnetic tape for a long time and can be replayed when necessary; Can store the information of multiple channels at the same time: has the ability to change the time base. Magnetic storage technology is widely used in scientific and technological information work and information service. Magnetic storage technology provides a material basis for small and medium-sized document information institutions to establish large-scale databases or information management systems, and creates conditions for establishing distributed microcomputer information networks.
2. Microform storage technology
It is the abbreviation of microfilm technology and one of the modern high-tech industries. Microform storage is to use a microfilm camera to shrink files and shoot them on film, and then save them as information carriers for later reproduction, distribution, retrieval and reading.
(1) Types of microreplications
According to its types, microreplication can be divided into two categories: roll and film. The film uses 16mm and 35mm silver halide negative microfilm as the recording medium. The length of the film is generally 30.48-60.96 meters. The roll film has low cost, large storage capacity, safety and reliability, and is suitable for large quantities of materials with low storage rate. Film can be divided into microfilm, strip, envelope, window card and so on. Microfilming can be divided into three types according to materials: Miao Hua silver film, diazo film and microbubble film. Silver halide film is made by coating latex containing photosensitive silver bromide or silver chloride particles on a plastic substrate. It is the earliest and most widely used film at present, and is generally used to make master films. For users, low-cost heavy chlorine film or micro-bubble film is generally used for laminating.
(2) Characteristics of microfilm storage technology
Since 1970s, microfilm technology has developed rapidly and been widely used. Its characteristics are: large information storage capacity and high storage density of microforms; Microforms are small in size and light in weight, which can save a lot of storage space and require less storage equipment; Microform has low cost and low price: Microform has a long shelf life, which can be kept for 50 years at a long temperature and for more than 100 years at a proper temperature; Microfilms are loyal to the original and are not easy to make mistakes; Using microform technology to store information can standardize and standardize the original documents with different specifications, which is convenient for management and computer retrieval.
(3) Application of Miniaturization Technology The most striking thing about Miniaturization Technology is that it combines with microelectronics, computer and communication technology, resulting in many new technologies and equipment with excellent performance. Combining microelectronics and copying technology with traditional micro-readers, an automatic retrieval and reading copier can be produced: COM technology can convert binary information output by computers into human-readable microscopic images and record them directly on the microscopic images; CIM technology can convert human-readable image data output by computer into computer-readable binary information medium, thus expanding the application scope of microfilm: CIR is an automatic image data management system, which can integrate the advantages of computer, microfilm and paper; CAR has the ability to retrieve any page from more than one million pages in one minute; Video microfilm system is a full-text storage and retrieval system of image data produced by combining microfilm, video and computer. It only takes 14 seconds to find any page of the original document. The combination of microform technology and optical disk technology can produce composite systems.
3. Optical disk storage technology
Optical disc is a kind of high-density data storage carrier which uses laser beam to read and write information on optical recording medium. It can store not only audio information, but also video (image, color, full-text information) information, which can also be stored and retrieved by computer.
(1) disc type
There are many kinds of optical disc products, which can be divided into the following categories according to their data reading and writing performance: First, CD-ROM has become an ideal medium for storing permanent multimedia information. The second type is a write-once optical disc (WORM), also known as a write-once optical disc. Users can record freely according to their own needs, but the recorded information cannot be erased. The storage system of WORM consists of WORM CD-ROM, CD-ROM drive, computer, file scanner, high-resolution display, tape or disk drive, printer, software, etc. Thirdly, the erasable and rewritable optical disc can erase and rewrite new information after writing information. The media used for this kind of optical disk include recording media with variable crystal phase structure and magneto-optical recording media.
(2) Application of optical disc technology
In information work, multi-functional and multi-form databases can be established by using CD-ROM technology, such as secondary literature database, patent literature database, audio-visual material database and so on. In information retrieval, you can use the CD-ROM information retrieval system to retrieve information, and you can practice and modify the retrieval strategy repeatedly until the retrieval results are satisfactory. The use of CD-ROM can promote the development of online retrieval, establish a distributed original supply system, save communication costs and achieve good economic benefits. Consultants can also use various CD-ROM database systems to provide users with various information retrieval and fast and high-quality consulting services.