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Cheat sheet for all computer connectors

Шпаргалка всех разъемов компьютера

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

To communicate with peripheral devices, one or more chips of the input-output controller are connected to the computer bus.

Cheat sheet for all computer connectors

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

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

The first IBM PCs provided

Built-in port for connecting a keyboard.

Up to 4 (COM1 ... COM4) serial ports (Eng. COMmunication), usually used to connect, relatively high-speed, communication devices using the RS-232 interface such as modems.

The following motherboard resources were allocated for them:

  • basic 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 Print Terminal), usually used to connect printers using the IEEE 1284 interface.

The following motherboard resources were allocated for them:

  • basic input / output ports: 370..37F (LPT1 or LPT2 only on IBM computers with MRA), 270..27F (LTP2 or LPT3 only on IBM computers with MCA] and 3B0..3BF (LPT1 only on IBM computers with MCA )
  • IRQ Number: 7 (LPT1), 5 (LPT2)

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

Serial ports were usually used to connect devices that needed to quickly transfer a small amount of data, such as a computer mouse and external modem, and parallel ones for a printer or scanner, for which a large volume transfer was not time-critical. In the future, 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 rate that does not satisfy the growing demand for data transfer between devices. As a result, new standards for USB and FireWire interface buses appeared, which were designed to replace the old I / O ports.

A feature of USB is that when connecting many USB devices to a single USB port, they use the so-called. hubs (USB hubs), which in turn switch between each other, 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’s motherboard, to which all daughter hubs (in particular, USB devices themselves) are connected.

The IEEE 1394 bus provides data transfer between devices with speeds of 100, 200, 400, 800 and 1600 Mbps and is designed to provide 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 in order to increase the speed of the interface, it is necessary to increase the frequency of its operation, and in the parallel interface this causes increased pickups between the parallel wires of the interface cable and requires a reduction in its length. In addition, the cable and connectors of the parallel buses are large.