I. Issa /EISA/MCA/VESA bus
ISA (Industry Standard Architecture) is a bus industry standard developed by IBM for 286/AT computers, also known as AT standard. The influence of ISA bus is very great. Until now, there are still a large number of ISA devices, and the latest motherboard has reserved a place for them. MCA (Microchannel Architecture) is a microchannel bus structure specially developed by IBM for PS/2 system. Because the license requirement violates the trend of PC development and opening up, it will fail before it is effectively promoted.
EISA (extended industry standard architecture) is an extended industrial standard of ISA bus designed by eisa group (composed of Compaq, HP, AST, etc.). ) for 32-bit CPU, and it is backward compatible with ISA, which was applied to high-end desktops that year. VESA (video electronics standards association) is an open bus designed by VESA organization (initiated by IBM and Compaq). And there are more than 120 companies participating) according to the Local Bus standard, but it is only a transitional standard suitable for 486, which has been eliminated at present.
Second, PCI bus.
After 1990s, with the wide application of graphics processing technology and multimedia technology, the graphical user interface (GUI) represented by Windows entered the PC, which required the PC to have high-speed graphics and I/O operation and processing capabilities, which challenged the speed of the bus. The original ISA and EISA bus can't meet the requirements, which has become the main bottleneck of the whole system. 199 1 In the second half of the year, Intel first put forward the concept of PCI (Peripheral Component Interconnection), and established a PCI group with more than 100 companies including IBM, Compaq, AST and HP. PCI is an advanced local bus, which has become a new standard of local bus and the most widely used bus structure at present. PCI bus is a local bus that is not connected to a specific processor. Structurally, PCI is a primary bus inserted between CPU and the original system bus. When necessary, the bridge circuit is used to realize the bus control of this level of intelligent equipment, so as to speed up the data transmission management.
Three. AGP bus
Although the graphics processing ability of PC is getting stronger and stronger now, the performance of PCI bus structure is still limited to complete detailed large-scale 3D graphics description. In order to make the 3D application capability of PC comparable to that of graphics workstation, Intel developed the AGP(Accelerated Graphics Port) standard, the main purpose of which is to greatly improve the graphics processing capability of high-end PC, especially 3D graphics. Strictly speaking, AGP cannot be called a bus, because it is a point-to-point connection, that is, it connects the control chip and the AGP graphics card. AGP provides a direct channel between the main memory and the display card, which enables 3D graphics data to pass through the PCI bus and be sent directly to the display subsystem. In this way, we can break through the system bottleneck brought by PCI bus and realize the drawing function of high-performance three-dimensional graphics. See figure 1 for the appearance of PCI and AGP slots. Types of standard interfaces
The use of standard interface technology in microcomputer system aims to facilitate the design of module structure, gain extensive support from more manufacturers, and facilitate the "production" of compatible external equipment and software. Different types of peripherals need different interfaces, and different interfaces are not universal. The interface standards that existed on 8086/286 computer before, such as ST506 and ESDI, have been eliminated. At present, the most widely used interfaces in microcomputers are IDE, e IDE, SCSI, USB and IEEE 1394.
I. Integrated Development Environment /EIDE Interface
IDE is originally integrated device electronics, that is, integrated equipment electronic components. It is a controller interface developed by Compaq Company and produced by Western Digital Company. IDE uses a 40-wire single cable connection. Because the controller is integrated in the driver, it is very simple to adapt the card. At present, the adapter card is no longer used in the microcomputer system, but the adapter circuit is integrated into the system motherboard, and a special IDE connector socket is left. IDE has been widely used in personal computer systems because of its many advantages and low cost.
IDE (Enhanced IDE) is an interface standard developed by Western Digital to replace IDE. In the microcomputer system with EIDE interface, the EIDE interface has been directly integrated on the motherboard, and there is no need to purchase an adapter card. Compared with IDE, EIDE has the characteristics of supporting large-capacity hard disk, connecting four EIDE devices and higher data transmission rate (above 13.3MB/s). In order to support large-capacity hard disk, EIDE supports three hard disk working modes: normal, LBA and large capacity.
Second, Ultra DMA33 and Ultra DMA66 interface
After the introduction of ATA-2 standard, SFFC introduced ATA-3 standard. The main feature of ATA-3 standard is to improve the security and reliability of ATA-2. ATA-3 itself does not define a higher transmission mode. In addition, ATA standard itself only supports hard disks, so SFFC will launch ATA-4 standard, which will integrate ATA-3 and ATAPI and support higher transmission modes. Before the ATA-4 standard was officially launched, Quantum and Intel launched the Ultra ATA(Ultra DMA) standard as a transitional standard.
The first standard of Ultra ATA is Ultra DMA33 (UDMA33 for short), and some people call it ATA-3. Motherboards and hard disks that meet this standard have been put on the market as early as 1997. At present, almost all motherboards and hard disks support this standard.
The second standard of Ultra ATA is Ultra DMA66 (or UltraATA-66), which is the latest standard proposed by Quantum and Intel in February 1998. Ultra DMA66 further improves the data transmission rate, and the burst data transmission rate can reach 66.6 MB/s in theory. Moreover, it adopts a new CRC cyclic redundancy check to further improve the reliability of data transmission, and uses an 80-pin bus (40-pin bus compatible with existing computers is reserved, and 40 ground wires are added) to ensure that the interference between adjacent signal lines is reduced in high-speed data transmission.
At present, Intel 8 10, VIA Apollo Pro and other chipsets provide support for Ultra DMA66 hard disks. Some motherboards also provide interfaces that support Ultra DMA66 hard disks. Most new hard disks support UltraDMA-66 interface.
Third, SCSI interface.
The original text of SCSI is small computer system interface, that is, small computer system interface. SCSI is also a system-level interface (as shown in Figure 2), which can connect various external devices that adopt SCSI interface standards, such as hard disks, scanners, optical drives, printers, tape drives, etc. These peripherals adopting SCSI standard must be equipped with corresponding peripheral controllers. SCSI interface was only used in small computers in the early days, but it has been widely used in PCs in recent years. Ultra3 SCSI's latest Ultra 160/m interface standard further improves the data transmission rate to 160MB/s/s ... Quantum also launched the first hard disks Atlas 10K and Atlas IV1kloc in June. SCSI should be a good configuration for PC. It is not only an interface, but also a bus. It is believed that with the further development of technology, SCSI will be widely used in microcomputer systems and peripherals such as EIDE.
Fourth, USB interface.
USB (universal serial bus) interface (the appearance is shown in Figure 3) is based on universal connection technology, which realizes simple and fast connection of peripherals, facilitates users, reduces costs and expands the connection range between PC and peripherals. At present, it seems that every device in a PC has its own set of connecting devices. The specifications of peripheral interfaces are different, and the limited number of interfaces can no longer meet the urgent needs of many peripheral connections. The key to solve this problem is to provide a * * * interface for devices to solve the general connection between personal computers and peripheral devices.
The application of USB technology is a major change in computer peripheral connection technology. At present, the USB interface standard belongs to the medium and low speed interface transmission, which is aimed at the medium and low speed equipment in the field of home and small office. Such as keyboard, mouse, joystick, display, digital speaker, digital camera and modem. In order to realize the universal connection of low-speed peripherals on a unified USB interface. Only one USB port is needed on the PC host, and other connections can be completed on the desktop through USB interface and USB hub. The USB system consists of a USB host, a hub, a connecting cable and a USB peripheral. The next generation USB interface will increase the data transmission rate to 120 Mbps ~ 240 Mbps, and support broadband digital camera devices and new scanners, printers and storage devices.
Verb (abbreviation of verb) IEEE 1394 interface
IEEE 1394 is a serial interface standard, which allows computers, computer peripherals and various household appliances to be connected very simply. According to the functional characteristics of IEEE 1394, it can be connected to a variety of different peripherals, which can also be called bus, that is, off-board bus connecting external devices. The prototype of IEEE 1394 is Fire Wire running on Apple Mac computer, which was adopted by IEEE and re-standardized. It defines the data transmission protocol and connection system, which can achieve higher performance at lower cost, thus enhancing the connection ability between computers and peripherals such as hard disks, printers and scanners, as well as consumer electronic products such as digital cameras, DVD players and videophones. Because the corresponding external devices need to have the interface function of IEEE 1394 to access the 1394 bus, it was not until the third quarter of 1995 that the digital camera introduced by Sony added the interface of IEEE 1394, and IEEE 1394 really attracted wide attention.
Sixth, the equipment bracket
Device Bay is a standard jointly developed by Microsoft, Intel and Compaq. This technology can make all devices work together, including CD-ROM, DVD-ROM, magnetic tape, hard disk drive and various devices conforming to IEEE 1394.
Because Device Bay technology can handle all kinds of devices, it can create a new PC: the motherboard will only include CPU, and all drivers and devices will be connected to the computer from the outside, including all high-definition multimedia, such as TV and telephone.
Although the specification of Device Bay was completed in 1997, it is likely to be stranded because of the high research and development expenditure of this technology. So far, Microsoft is not ready to support the specific plan of DeviceBay in future operating systems.