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Crib of all computer connectors

Шпаргалка всех разъемов компьютера

The (personal) computer port is designed to exchange information between devices connected to the bus inside the computer and an external device.

To communicate with peripheral devices, one or several I / O controller chips are connected to the computer bus.

Crib of all computer connectors

Other additional devices (mouse, printer, scanner, etc.) can be connected to the personal computer. Connection is made through the ports - special connectors on the rear panel.

Ports are parallel (LPT), serial (COM) and universal serial (USB). On the serial port information is transmitted bit by bit (more slowly) on a small number of wires. A mouse and a modem are connected to the serial port. The parallel port information is transmitted simultaneously by a large number of wires corresponding to the number of bits. A printer and a portable hard drive are connected to the parallel port. A USB port is used to connect a wide range of peripherals - from the mouse to the printer. It is also possible to exchange data between computers.

The first IBM PCs provided

Built-in port for connecting the keyboard.

Up to 4 (COM1 ... COM4) serial ports (COMmunication), usually used for connecting, relatively high-speed communication devices using RS-232 interface, for example modems.

The following motherboard resources were allocated to them:

  • base I / O ports: 3F0..3FF (COM1), 2F0..2FF (COM2), 3E0..3EF (COM3) and 2E0..2EF (COM4)
  • IRQ number: 3 (COM2 / 4), 4 (COM1 / 3);

Up to 3 (LPT1 .. LPT3) parallel ports (Line Line Terminal Engl.), Usually serving to connect printers using the IEEE 1284 interface.

The following motherboard resources were allocated to them:

  • I / O base ports: 370..37F (LPT1 or LPT2 only in IBM computers with MRA), 270..27F (LTP2 or LPT3 only in IBM computers with MCA] and 3B0..3BF (LPT1 only in IBM computers with MCA )
  • IRQ number: 7 (LPT1), 5 (LPT2)

Initially, the COM and LPT ports on the motherboard were physically missing and were implemented with an additional expansion card inserted into one of the ISA expansion slots on the motherboard.

Serial ports were typically used to connect devices that needed to quickly transfer a small amount of data, such as a computer mouse and external modem, and parallel ports — for a printer or scanner for which large volume transmission was not time critical. Later on, support for serial and parallel ports was integrated into chipsets that implement the logic of the motherboard.

The disadvantage of the RS-232 and IEEE 1284 interfaces is the relatively low data transfer rate, which does not satisfy the growing demand for data transfer between devices. As a result, new standards for USB and FireWire interface buses have appeared, which were designed to replace the old I / O ports.

A special feature of USB is that when many USB devices are connected to a single USB port, they use so-called. hubs (USB hubs), which in turn commute with each other, thereby increasing the number of USB devices that can be connected. This USB bus topology is called a “star” and also includes a root hub, which, as a rule, is located in the “south bridge” of the computer motherboard, to which all child hubs are connected (in particular, USB devices themselves).

The IEEE 1394 bus provides data transfer between devices at speeds of 100, 200, 400, 800 and 1600 Mbit / s and is designed to ensure comfortable work with hard drives, digital video and audio devices and other high-speed external components.

FireWire, like USB, is a serial bus. The choice of the serial interface is due to the fact that to increase the speed of the interface, it is necessary to increase the frequency of its operation, and in a parallel interface this causes an increase in pickups between the parallel cores of the interface cable and requires a reduction in its length. In addition, the cable and connectors of parallel buses have large dimensions.