Entry and exit point for data from the system
Connects the system and a device using a connecting cable
Located at the back or the front side of the system case
Ports have different shapes and sizes and you can not insert a plug in the wrong port
You can just unplug a device that is not used and plug in another device in that port
Identifies the type of the port
Serial Port :
Sends and receives one bit of data at a time
Known as the Communication or COM port
Has 9 or 25 pins
Connect devices such as the mouse, plotters and modems
Transmitting device sends a start bit then actual data byte followed by a stop bit
Maximum cable length is 50 feet
If you need more serial ports, you can install multi I/O card
Parallel Port :
Transmits eight bits of data at a time
Has 25 pins
Connects devices such as printers, scanners, external hard drive and tape drive
You can get more parallel ports by installing an expansion card
LPT1 uses IRQ7 and LPT2 uses IRQ5
Different types of parallel ports are :
IEEE 1284 :
Compatibility Mode – used for directing data from computer to peripheral (output only)
Nibble Mode – 4 bit (Input only)
Byte Mode – uses software drivers same as nibble mode (8 bit)
Enhanced Parallel Port Mode (EPP) – it is hardware driven and bi-directional, high speed parallel port interface
Enhanced Capability Port Mode (ECP) – same as EPP uses DMA
PS/2 :
Used to connect the keyboard and the mouse
Available in a color that matches the color of the device plug
Uses 6 pins to connect the device
Universal Serial Bus (USB) :
Connects upto 127 devices to a single port
Supplies power to the device
Plug-and-play support
Maximum cable length is 30m thus you can connect 5 hubs to the USB
Has two different connections: connection A and connection B
USB 1.0 – 1.5 Mbps, USB 1.1 – 12 Mbps and USB 2.0 – 480 Mbps
Infrared Ports :
Communicate with the system without using wires
Devices send out infrared signals that enter the system through this port
Bluetooth Port :
Allows wireless communication between devices within a ranged distance
Uses 2.45 GHz frequency range for data communication
A Bluetooth adapter required for the computer and a Bluetooth compatible device to communicate
Speed is 1 or 2 Mbps depending on the version
IEEE 1394 Bus :
Enables fast and high serial data transfer rate of upto 400 Mb per second
Connects and supplies power to the connected devices such as printer, scanner, web camera and generally used for transferring audio and video data from a camera to the system
Known as FireWire by Apple and iLink by Sony
Connects computer to wireless LAN
By using this adapter desktop, notebook and laptop users can connect to a standard mobile network
Plugged to computer through a USB port
Data Transfer Rate is 54 Mbps
While using the device, errors may occur if there is a problem with the I/O port
Different types of problems related with IO port :
