Now there is no uniform standard for the interface of the computer system to connect the peripheral device. If the keyboard is used with a PS / 2 interface, the printer is connected to the parallel interface of 25 pins, and the mouse is used to use a serial or PS / 2 interface. USB will unify these different interfaces and use a 4-pin plug as a standard plug. Through this standard plug, all peripherals can be connected in the form of chrysanthemum chain and will not lose bandwidth. The USB specification is divided into five parties: controllers, controller drivers, USB chip drivers, USB devices, and client drivers for different USB devices. According to the device demand for system resources, four different data transfer methods are specified in the USB specification: isochronous, interrupt transmission mode, control transmission mode (Control) and batch (BULK) transmission Methods, these transmission methods are characterized, which are used in different places. USB requires support for host hardware, operating system, and peripheral support to work. At present, the motherboard generally uses a control chipset that supports USB function, and a USB interface socket is also installed. The Windows98 operating system has built-in support for USB functions (but WindowsNT does not support USB). There are already digital cameras, digital speakers, digital game rods, printers, scanners, keyboards, mouses, and many other USB peripherals. As a large number of popularization of USB's personal computer, USB has gradually become a standard interface of the PC. It is already a general trend. The latest PC is almost 100% support USB, and the device using the USB interface is also developed in an amazing speed. USB is the abbreviation of English Universal Serial Bus, and the meaning of Chinese is a "universal serial bus". It is not a new bus standard, but applies new interface technologies to the PC field. As early as 1995, there was already a PC with a USB interface, but because of the lack of software and hardware equipment support, these PCs' USB ports were idle unused. In 1997, Microsoft began to support USB support in Win95OSR2 (Win97). After 1998, Microsoft built into a support module for USB interfaces in Windows 98, plus USB devices, USB step by step Into the practical phase. The history and development of USB is talking about USB technology, let us take a look at the development history of peripheral interface technology. There is no change in the function and structure of the serial port and parallel port of the personal computer over the years. The appearance of the serial port is in 1980, the data transmission rate is 115kbps ~ 230kbps. The serial port is generally used to connect the mouse and external modem; the data transfer rate of the parallel port is 8 times faster than the serial port, the data transfer rate of the standard parallel port is 1Mbps, generally used To connect printers, scanners, etc. In principle, each peripheral must be inserted on an interface. If all the interfaces are used, they can only add the interface by adding a card. String parallel ports are not limited speed, but it is very inconvenient in use. In 1994, in 1994, seven world-renowned computer and communication companies such as Intel, Compaq, NEC, Northern Telecom have set up a USB Forum, spent nearly two years, has formed a unified comment, November 1995 The USB0.9 Universal Serial Bus specification was formally established. In 1997, there was a periphement that truly met USB technical standards. USB1.1 is currently launched in a standard in supporting USB computers and peripherals. At the beginning of the INTEL's Development Forum in 1999, participants introduced USB2.0 norms. In addition to the original Compaq, Intel, Microsoft and NEC, there are HP, Lucent and Philips in addition to the original Compaq, Intel, Microsoft and NEC. new member.
USB2.0 is compatible downwardly USB1.1, the transfer rate of data will reach 120Mbps ~ 240Mbps, and also supports wideband wide digital camera and next-generation scanners, printers, and storage devices. The USB1.1 currently used is mainly applied to the medium and low speed external equipment, which provides the transmission speed with low speed 1.5Mbps and full speed 12Mbps, low speed USB bandwidth (1.5Mbps) supports low speed devices, such as a display, modem, Keyboard, mouse, scanner, printer, optical drive, tape drive, floppy drive, etc. Full speed USB bandwidth (12Mbps) will support a wide range of multimedia devices. After USB, another interface technology called FireWire (ie, IEEE 1394) is from the laboratory into the market area, which is more powerful than USB functions than USB functions. IEEE 1394 is also an efficient serial interface standard. IEEE 1394 can connect up to 63 devices on one port, and a tree or chrysanthemum chain topology is used. The IEEE 1394 standard defines two bus patterns, namely: BackPlane mode and Cable mode. The BackPlane mode supports transmission rates of 12.5, 25, 50 Mbps; Cable mode supports the transfer rate of 100,200,400 Mbps. 1Gbps version is currently being developed. Now, support USB's PC and peripherals are increasing, and USB on software has also become a key component of Windows 98, and will soon be supported in Windowsce and Windows2000. The Apple's operating platform has already provided support for USB, which is expected that the platform of Sun and Digital will also provide support for this technology. The USB features and the application USB can be widely supported and rapidly popular, because it has many of the following features: 1. Convenient use of USB interfaces to connect multiple different devices, support hot-swappable, in software, Usb designed drivers and applications can be automatically started without user intervention. USB devices do not involve IRQ conflicts, which use their own retention interrupts alone, and will not share resources with limited PCs with other devices, and save users' troubles. USB devices can truly "plug and play". 2. Speed speed and fast performance is one of the prominent features of USB technology. The highest transfer rate of the USB interface is currently up to 12MB / s, which is 100 times higher than the serial port, which is more than ten times higher than the parallel port. The speed of USB will also increase to 100MB / s in the future. 3. Connecting the flexible USB interface supports a string-column connection of multiple different devices, one USB port theory can connect 127 USB devices. The way the connection is also very flexible, or both serial connections can also be used in the middle pivot connector (HUB), and multiple devices are connected together, and the USB port of the PC is again connected. In USB mode, all peripherals are connected outside the chassis without having to turn on the chassis; allowing peripheral hot plugging without having to turn off the host power. USB uses a "cascaded" mode, that is, each USB device is connected to a USB plug to a peripheral USB outlet, and itself provides a USB outlet for a USB peripheral connection. Through this similar chrysanthemum chain, a USB controller can be connected to up to 127 peripherals, and each peripheral distance (cable length) can reach 5 meters. USB can also intelligently identify access or disassembly of peripherals on the USB chain. 4. Independent Power Supply Commonly Use the serial port, and the equipment of the parallel ports require a separate power supply system, and the USB device does not need because the USB interface provides a built-in power supply. The USB power supply provides 5V power supply to the low voltage device, so the new device does not require a special AC power supply, thereby reducing the cost of these devices and improves cost performance.
5. Support multimedia USB provides two data support for the phone, USB supports asynchronous and isometric data transfer, allowing phones to integrate, share speech mail, and other features. USB also has high fidelity audio. Since the USB audio information is generated outside the computer, the chance of electronic noise interference sound quality is thus reduced, so that the audio system has a higher fidelity. 6. The problem exists, although in theory, USB can achieve a series of serial connections up to 127 devices, but in practical applications, maybe in series 3 to 4 devices can cause some devices to fail. And most USB products, only one input port is not connected to the next USB device. In addition, although the USB itself can provide 500mA current, once the high power consumption is encountered, it will lead to insufficient power supply. The way to solve these problems is to use USBHUB, but the price of HUB is still too expensive. Usb Application So far, USB has been applied on a variety of peripherals of the PC, including scanners, digital cameras, digital cameras, audio systems, displays, input devices, and more. Scanners and digital cameras, digital cameras are the earliest products from USB. Traditional scanners, the user must start the image processing software and scan drive software before performing scan operation, and then operate the scanner through the software. The USB scanner is different, and the user only needs to be scanned, press the scanner button, and the scanner driver software and image processing software are automatically popped up, and the scanning process is monitored in real time. USB digital camera, camera more benefit from USB's high-speed data transmission capability, making large capacity image file transfer can be done in a short time. USB's representative of the audio system application is Microsoft DigitalSound System80 (Microsoft Digital Sound System 80) launched by Microsoft. Using this system, you can transfer the digital audio signal to the speaker, no longer need a digital-to-mode conversion, and the sound quality is also improved before it. USB technology is very stable on the application on the input device, the USB keyboard, mouse, and the game pole are extremely stable, and there are very few problems. As early as 1997, a display with a USB interface has appeared, providing additional USB ports for the PC. This is mainly because most of the PC sections are desktop devices, which are more convenient and simple to connect to the same host connection. The USB device that appears in the market is also USB MODEM, Iomega USB ZIP drive, and ETEK USB PC network card, etc. For laptops, the use of USB interface is more significant, and the general USB interface not only makes it easy to connect the laptop, but also makes laptop manufacturers no longer need to resettle different interfaces on the motherboard for different parts. This makes the main board, the number of components, and the complexity of the complexity have different degrees of cut, thereby improving the heat dissipation problem in the system operation. It will also promote higher frequency processors to quickly apply in the mobile computer, making the gap between the laptop and the desktop PC will be further reduced. USB applications will be more and more wide, some industry people even forecast, future PCs will be a sealing device, all peripherals will be connected via USB or other external interface. The Chinese name of UU12288 USB (Universal Serial Bus) is called "Universal Serial Bus". This is a new interface technology widely used in the PC in the past two years. In theory, USB technology consists of three components: a PC system with a USB interface that supports USB system software and devices using a USB interface. In 1997, Microsoft launched WIN95, Win97, USB entered the practical phase, but because the support of the USB belongs to the plug-in module, the support module of the USB interface is really mature after Win 98 is launched. Therefore, in a sense, Win98 became the "promoted Po" of USB technology development and application.
Due to the simple installation, easy to use, according to DataQuest statistics, only 10 million USB equipment sold only last year, this figures will increase to 50 million units this year, and this number can be nearly 100 million in 2000 station. UU12288, UU12288, UU12288 Currently, new motherboards typically only have two built-in USB interfaces (Figure 1), to connect more than 4 USB devices, USB HUB (Figure 2), through USB HUB Expand the number of USB interfaces. Everyone is not unfamiliar with HUB, plus a USB in front, the function is exactly the traditional product, but it belongs to the inherent hub in a certain field. USB HUB can connect to a USB device while it can also be connected to another USB HUB. However, USB HUB cannot be more than three in succession. From the specification, you can connect up to 127 devices through USB. This number is actually theoretical, who will connect more than 100 peripheral devices on a computer (what can be installed). Therefore, the installation of USB HUB is also compared to "fool". The first step is to start the USB interface on the motherboard. Check the USB option in the CMOS Setup, if you are dropped by Disabled, change this option to Enabled, and you can find a USB controller after re-entering Windows. The general HUB has a pair of two, one-to-four, one-to-five types. The so-called pair of two is through the original USB interface, expands two USB interfaces. Said a pair of two, but since the original USB port is occupied, although the two interfaces are expanded, only one USB interface is substantially larger (see Figure 3). According to this type, a pair of four can be three USB interfaces, and a pair of five can be more than four USB interfaces (the more Hub's price is of course, the higher the relative power consumption will also increase) . With a pair of USB HUB installed as an example, this USB HUB has 1 input connector and 4 output connections (see Figure 4). The output connector is less than the input connector, it is easier to distinguish. At the same time, the wire connecting the USB device is generally provided with the HUB, and the joint at one end of the wire is used to connect the input of the USB device (or USB HUB); relative, the joint of the other end of the wire is used to use USB HUB The part of the output is connected, and the installation is sequentially installed. It is worth noting that many USB devices now have the function of USB HUB. The author has seen such a new type of monitor (17 inches), with four USB output connections on the back of the cabinet (of course, there is a USB input connector), it is clear that this monitor can also take a USB HUB Responsible. Another point is the power supply, a pair of two USB HUB usually does not have an external power supply, and a pair of USB HUBs are attached to the power adapter, but a pair of USB HUB does not take power to work, just every The interface can only power about 100 mA, and once the power adapter is connected, it can be raised to about 500 mA. The power supply is mainly dependent on the user itself. I suggest that when you install, the high power consumption is on the computer's USB interface, which will not need a power supply to still function properly, the USB device, such as the mouse. , MODEM, etc., to one-to-four USB HUB. UU12288 II, Upgrade Your USB UU12288 For those users who have no built-in USB interfaces, it is not equal to usb. Users can upgrade their own computers by purchasing a USB interface card, making it USB feature.
The USB card that is often visible in the market is now the PCI card, bringing two USB ports, you only need to put this card into the PCI slot of the motherboard, the driver software that is attached to the card is OK. Specific installation is simple, do not have any power cords and signal lines, like installing the graphics, the sound card, as long as plugging. At present, a famous manufacturer of USB cards on the market is generally two, and one is entrega, and the other is Belkin, and the quality is OK. UU12288 III, USB Installation Example UU12288 So far, USB has been applied, outputting equipment, including scanners, digital cameras, digital cameras, audio systems, displays, and more. Scanners, digital cameras and digital cameras are the highest in USB technology. The rapid follow-up of these products is mainly due to the high-speed data transmission capability of USB "one touch", so that large-capacity image transfer can be done in a short time. In terms of entering the device, the USB keyboard, mouse, and the game rod are extremely stable, rarely problems. In addition, there are DSL USB "Cat", Iomega USB ZIP drive, and ETEK USB PC network card, etc. In particular, more and more laptops have also been armed for USB interfaces, which is not to say how much the laptop can get from the USB interface, and the key is those users who often transfer data between desktops and laptops. You can save a lot of time using USB. The following is described as an example of the Mai Bao USB sound card. UU12288 opens the package, you can see this USB sound card is quite like a mouse. However, it is different from the mouse. There are two connectors under the butt, and one is used to connect the USB socket, and the other is used to connect the speaker. Like all USB devices, the installation of this USB sound card is very simple, just connect this card into the USB interface, restart the computer, Win98 automatically detects the device, and automatically installed the Win98 Drivers. Since it is a USB device, the card also supports hot-swapping, and it is not necessary to shut down. UU12288 is audition, on PII300 / 64M / PC Work4.1, the overall sensing sound quality and sound effect are not bad. But in some games that support A3D, compared with high-grade sound cards such as Diamond MX300, it is obviously not optimized. At the same time, this USB sound card is low, which also makes it slightly lack of overall grade. UU12288 IV, USB exists UU12288 or more introduced USB's many places, of course, USB is not happy. The first is the problem of connection. When you purchase a USB peripheral, you should try to use all USB interfaces on the motherboard. According to past experience, it is sometimes inserted into a USB peripheral to cause the system to crash when the USB interface has never been used. In addition, the USB standard specifies that the external device can be connected in the form of a chrysanthemum chain, which requires all products to have two USB interfaces, but now many USB peripherals have only one interface, so that other USB products cannot be connected in series USB bus. As we have already said earlier, now some USB monitors can provide 4 ports USB HUB function, and the market can now see the keyboard with USB HUB functionality to provide two USB interfaces. But even so, I still recommend that you save the USB interface. If you let the keyboard, the mouse, the handle accounts for the original number of USB interfaces, after digital camera, scanner, camera, etc., the device, etc., Send all the hubs is not the policy, after all, there is a lot of money. Another problem is the power supply problem of USB products.
Although the USB bus can get rid of us from the entangled cable, the signal line of the signal line, the USB interface on the PC computer often does not provide a power supply of more than 4 USB peripherals. Therefore, when there is a plurality of USB products at the same time, it is necessary to consider plus a powered USB hub. The proposing of the USB (Universal Serial Bus) interface (Figure 3) is based on the use of universal connection technology, achieving a simple and quick connection to peripherals, reaching the user, reducing cost, and expanding the scope of the PC connection peripheral. At present, it seems that each device has its own connection device. The specifications of the peripheral interface, the limited number of interfaces, can no longer meet the urgent needs of many peripherals. The key to solving this problem is to provide a shared interface of the device to solve the universal connection of your personal computer with the peripheral device. UU12288 USB technology application is a major change in computer peripheral connection technology. Now the USB interface standard is a medium and low speed interface transmission, facing the middle and low speed devices in the family and small office. For example, keyboard, mouse, joystick, display, digital speaker, digital camera, etc., the purpose is to implement unified USB interfaces to implement universal connections in low speed peripherals. Only one USB port is only required on the PC host, and other connections can be done on the desktop via the USB interface and the USB hub. The USB system consists of a USB host (HOST), a hub, a connection cable, a USB peripheral. The next-generation USB interface, the data transfer rate will increase to 120Mbps ~ 240Mbps and support broadband wide digital camera and new scanners, printers and storage devices. Although earlier in 1997, the Intel 440 LX chipset provided USB function, but because the USB has little equipment, this technology did not cause too much attention to users. Today, the number of devices that support USB is considerable, and the advantages of USB interfaces are highlighted. In the PC99 specification, USB is already one of the standard devices of PC. It can be foreseeable that there will be no annoying peripheral interfaces such as PS / 2, COM on the main board, replaced by several USB interfaces, all peripherals are connected. In fact, this year is a very popular IMAC. Its keyboard and mouse use the USB interface, very avant-garde, but the PC users don't need to red, now there is a lot of USB devices to choose, now let's take a look. These era coordinate products. USB speaker uu12288 now has many manufacturers with USB speaker production capacity, more famous "jazz" speakers with J-S descent electronic, walk, wheat blue. The current market is more popular with J-S J6502 and the rambler's USB1900T / USB1000TC. The R1900 / R1000 of the UU12288 is a typical wooden speaker, providing two analog signal input interfaces, a USB digital signal input interface. In addition to a USB interface, there is no change in other aspects. A USB control circuit board in the lattice of the speaker, from the form, it is to move a USB sound card from the outside to the inside of the speaker. The J6502 of uu12288 Cevese Electronics is also a plastic speaker with a USB interface with an analog signal input interface. Talking about the plastic speaker, ordinary users have a misunderstanding, thinking that the wood speaker must be higher than the quality of the plastic speaker. In the past, this idea may be correct, but with the continuous improvement of plastic materials, its density can be designed to the acoustic requirements, and in some are not very professional, the plastic speaker has begun to emerge. Most importantly, plastic speakers can make a variety of personality appearance (everyone rarely see a variety of wooden speakers), with the whole computer and peripherals to harmony, and most foreign multimedia speakers use plastics The speaker is also the truth.
From the sound performance, the J6502's high-calorie is more realistic, the bass effect is still, but its shock is not enough, but for multimedia speakers placed on the computer desk, the sound quality performance can fully meet the user requirements. USB Sound Card UU12288 The popular A3D and EAX environment sound technology and 64-bit DLS waveletries make users very satisfied, and the space for the vendor to play an imagination of the sound card is getting smaller and smaller. However, USB's popularity makes some vendors who dig unique to find some selling points to attract the scent of the user. The appearance of the USB sound card is the masterpiece of these vendors. UU12288 USB sound card meets the taste of users who have bought traditional analog speakers but want to taste digital audio technology. Due to the USB interface, the USB sound card becomes an external device. The principle of Voice of the USB sound card is simple: obtaining digital audio from the USB interface, and outputs it to the traditional speaker through the D / A (number / model) conversion of the USB sound card. UU12288 compared to the traditional sound card, the USB sound card has the following advantages: (1) The source of the signal is different. The traditional sound card signal is derived from the digital audio file, the CD-ROM audio, or other analog audio signals, and the USB sound card signal is derived from the digital audio signal of the USB interface. (2) The electromagnetic interference from the analog signal output to the speaker is smaller. The USB sound card is outside the computer chassis, the distance between the sound card and the speaker is closer, and the electromagnetic interference from the analog audio signal is smaller, and of course its sound quality will be better. • USB sound card installation is more convenient and simple, no need to open the chassis, say that the USB sound card is not essentially different compared to the traditional sound card, but the interface has changed, this change is just to comply with the big trend of USB equipment. There is no breakthrough in performance. UU12288 author has a USB sound card of a wheat blue company, appearance looks like a USB mouse, just a sound line that receives the speaker. However, to make the USB sound card work normally, "Digital Audio" in "Control Panel" / "Multimedia" / "CD Music" in Windows must be set to work. Otherwise, it may not pronounce the CD / VCD. After opening the case of the USB sound card, you can see that the USB sound card layout is very simple, only one D / A (digital / mode conversion) chip, manufactured by the famous Philips, and some of the other capacitors, resistors. Now there are several companies to produce this D / A audio chip, while several chips of Philips occupies the mainstream of the market, namely UDA1321, UDA1325, UDA1331, UDA1335, and the details of their chips can be used to http: // www_eu2. Semiconductors.com/Handbook/chapter_1955.HTM website is seen. UU12288 author believes that the USB sound card will be divided into a piece of a cup from the traditional sound card market, but the traditional sound card technology is mature, the interface is also relatively rich, such as the MIC, JOYSTICK interface, etc., it is estimated that the sound card market will continue. time. USB printer uu12288 The biggest advantage of a printer with a USB interface is to easily connect the PC, Macintosh, and IMAC without having to worry about the interface type problem. UU12288 EPSON is the old-name printer manufacturer, and the USB technology has not fallen, the USB interface is almost the standard configuration of the company's printer. The EPSON Stylus Photo 750 is an excellent inkjet printer with a USB interface.
The Photo 750 uses EPSON unique micro-pressure printing technology (Micro Piezo), which can minimize 6 microllyurized ink drops (1 micro-liter = 1 10-12 liters) printing, then the diameter of the ink droplets is only 1 hair 1 / 4, the naked eye is almost impossible. In order to protect the printing speed, Photo 750 uses intelligent ink droplet conversion technology to automatically adjust the size of the ink droplets, using large ink drops in the high concentration region, and two-way printing and increasing nozzles to improve the printing speed. UU12288 Since the printer's speed bottleneck does not transmit data part to the printer, it is not great to use a USB interface to bring it. Its USB interface should be said to be a feature of the brocade. USB Scanner UU12288 USB relative to other traditional interfaces, its fast data transmission capability and installation simple harmonious balance are reflected in the scanner. The scanner installation of the traditional SCSI interface is extremely troubles, and the requirements for the computer are harsh, and there must be a SCSI interface, and the data transmitted in parallel is very slow. The USB interface can meet the user requirements from the simple aspects of speed and installation. The current mainstream scanner manufacturers began to produce USB scanners, such as HP Scanjet 5200c, ACER's ACERSCAN 310U, TARGA TS12MU. This USB scanner launched by uu12288 Targa has a transparent housing, which scans the maximum size of A4, and the optical resolution is 6001200dpi. The main advantage of this machine is that the following: (1) USB interface can effectively improve data transmission speed. (2) No external power supply design, due to the adoption of CIS technology, the power consumption is only 2W, is suitable for business trips. (3) Ultra-thin ultra-light design, green transparent shape design, and pleasing shape. UU12288 TS12MU scanner fully reflects the development direction of future scanners. USB camera uu12288 At present, the image quality of the camera cannot be compared with digital cameras. The most important thing is that the image transmission speed is slow, which is why the camera is delayed. Early camera is connected to the computer through parallel ports or serial ports, the data transmission speed is extremely slow, and the worst is to obtain power ( 5V) from the keyboard or mouse outlet (the author used a handwritten pen, connection The complexity of 5V power supply makes me a DIY fan that is not bad. The video situation is naturally terrible, the loss of frame is serious, it seems to always be uncomfortable to the owner's movement. UU12288 camera manufacturers have noticed this deadly shortcomings, and they have put into research and development power to improve their products. However, before the USB interface has become a popular bus, the results they have achieved are not large, "uncommeted fixed" is still in almost all camera products. After 1998, the camera products launched by manufacturers such as Creative, Logitech, NEC are the USB interface. Compared to traditional other interface cameras, the camera advantage of the USB interface is obvious: support hot-swappable, the speed of transmission data is faster because of transmission The rate of increases, the resolution of the image can also be done, and the improvement of image quality is also possible. UU12288 now has a "masterpiece No. 2" camera, the image quality is good, and there is a digital camera camera function. Specific performance testing can be seen "Who is brighter" on "Who is the eyes" on "Computer News". USB keyboard, mouse uu12288 keyboard and mouse calculates the minimum device from USB, there is no need to use the USB interface, because the current motherboard provides a keyboard and mouse-specific PS / 2 port.
However, USB will finally replace the PS / 2, and you will feel the new product is also good. UU12288 Microsoft's new ergonomic keyboard uses USB interface, compatible with PC and IMAC, no matter how top, feel is unacceptable, but it cannot be used under the DOS system. Since there is no surprising advantage of the keyboard of the USB interface, there is also a company to add a point of function, and the USB keyboard manufactured by CHERRY has built the HUB of 4 USB interfaces, which can connect 4 low-power USB devices, such as mouse, flying Rod, etc. UU12288 Logitech should be considered a boss in mouse manufacturers. Silver and spiramuses using the USB interface are proud of Logch Company. Both mouse provide a pin header of USB to PS / 2, and the motherboard does not support USB users can also be used. The deep gray sprinkle is more slender, the line is beautiful, double button plus a wheel, and the left-hand user is also applicable. Silverhead with ergonomic design is suitable for right-handed users, with a button, which is more reasonable than the ordinary three-bond mouse. After using the Logiteram Mouse, the author feels that the feel is very good, the accuracy is very good. The only less than the silver might may be the design of Westerners, and the author is a little bit a little bit. All buttons of these two mice can be customized. Each button has more than 50 functions. You can choose from the MouseWare control center software of Logitech, which can be adjusted and powerful. The USB mouse and the PS / 2 mouse are not too big. The hot-swappable opportunities is relatively small, but the Logitech silver scrape and the spiral offer USB and PS / 2, which is more choice than a single interface. USB Display UU12288 The current USB display is not actually transmitted by the USB bus as a USB bus, but it still uses a graphics card, so it can only be counted as a "display of USB functions". UU12288 LG795FT PLUS is such a display, via a USB interface, users can use software to adjust some display properties, including screen size, screen position, distortion, color, etc., without having to use an OSD menu. When using the USB display item that is displayed, you can drag the slider with the mouse, which can be set to most of the functions that need to be adjusted by the OSD menu. More importantly, it has built a 4-port USB Hub (integrator), which can save you a spending. The author believes that the USB display at this stage has not actually significant, and the 795ft plus built-in HUB is obviously more attractive than the USB function provided. USB MODEM UU12288 briefly said that modem's role is to modulate the digital signal of the computer into an analog signal transmitted on the telephone line, and the USB Modem is also the same, but its structure is much simpler than ordinary external Modem. UU12288 author tried Lianbao's "small black cat" 56K USB MODEM, from the appearance, this MODEM handle black, very small, only one mouse size, and common external 56k modem is completely different. "Small Black Cat" does not require an external power supply, and both ends of Modem have a USB interface and telephone line interface, respectively. In use, the performance of USB Modem is not bad, and the connection speed has been stabilized at 52000 bps and rarely appears. However, its CPU usage is more than normal 56K modem, especially when opening the web page, the CPU usage is about 50%. This USB MODEM does not have a photo interface, which means that if the user is not using a special telephone online, it is necessary to exchange the telephone line between the phone and modem, no ordinary modem is convenient.
UU12288 Because the price of USB Modem is cheaper than ordinary modem, the price is relatively high, it should be one of the more USB peripherals. USB Flood Drive UU12288 3.5-inch USB floppy drive is one of the less peripherals in China, and practicality is not strong. After all, most computers have a built-in floppy drive. VSTTECH's 3.5-inch floppy drive is originally designed for iMac, but it is fully compatible with the 3.5-inch disk of the PC. As long as your PC supports USB, it can be used as a normal flourish. This floppy drive is used in the same translucent shape as IMAC, very beautiful, and the transmission rate is increased to 500kb / s. UU12288 ZIP drive is relatively rare in China, but in Europe, the European and American is relatively popular, it uses a special 100MB or 250MB ZIP disk, capacity, speed, and reliability and 3.5-inch floppy drive cannot be synonyby. The built-in ZIP drive uses the IDE interface, which is obviously more advantageous than the USB interface, but it requires a 3.5-inch drive space in the chassis, and most brands do not have this condition, so the zip driver is dominated by external, and the interface includes parallel. Port, Ultra SCSI and USB. The continuous data transfer rate is 0.8Mb / s, 2.4Mb / s and 1.2Mb / s, we can see the fastest drive of the SCSI interface, but a SCSI interface card value is worthless, from the price / performance ratio, USB interface The ZIP driver is obviously the best choice. The new Iomega Zip USB drive has averaged 29ms, 100MB of capacity, which is extremely role in data movement. The function of the USB network card uu12288 USB network card is better than the PCI network card we use, the price is not very suitable, but it is also a member of the USB family. The USB network card currently provides 10Mbps LAN connection, while larger LAN is now using a 100Mbps connection, so it is more suitable for home or small offices. At present, the price of the USB network card is very high, even more expensive than 100MB PCI network card, which is not much practical value for domestic ordinary users, but it is useful for laptop users with USB interface. In addition, there is a USB TO USB pair, which allows two computers to communicate with each other through the USB interface, providing a higher connection speed than serial port, and the USB network card, I think it is a more practical device. . USB transfer device uu12288 USB transfer device has a lot of type, mainly to provide a conversion function of USB interface and other interfaces, including USB TO ADB, USB to PS / 2, USB TO SCSI, USB TO Serial, USB Type A to B, etc. Wait. These adapters can use other non-USB interfaces to be used on USB ports, which seem to have too many uses today, but when they only provide USB interfaces on the one-day motherboard, they have a land. There are two more practical USB adapters, one of which is the USB to PCI interface card. Its function is to provide two USB interfaces for non-support for USB but supports PCI, or for the PCI. Only two USB interfaces (such as Intel 440bx, etc.) provide additional two USB interfaces, but to take up a PCI slot. Keyspan's products use Opti chips, Cablemax's products use VIA chips, they all support USB high-speed and low speed connections, no jumper design, automatic setting IRQ, users only need to plug in PCI slot and install drive software . Another practical USB adapter is a USB device extension cable.
