Introduction to Computer Peripherals, Input-Output Ports, and Video Display Interface

  • Computer peripherals can be input devices such as mouse, keyboard, and scanners; output devices like printers, projectors, and monitors; or input-output devices like touchscreens and external storage drives. These peripheral devices use connectors, some of which are cabled, to connect to the motherboard.
A computer monitor, wired keyboard, and wired mouse.
  • Printers print text and photos onto papers and other printable materials. There are various types of printers:
  1. Inkjet Printer – This is a personal printer that uses inkjet technology which sprays ink droplets in a specified pattern onto the pattern in order to reproduce a text or image.
  2. Laser printer – It can handle larger print loads than the inkjet printer, and also produces better print quality. It burns a special type of ink known as toner onto the paper to reproduce text or image.
An inkjet printer.
A laserjet printer.
  • The USB port provides a universal access connector for the largest number of peripherals.
  • The Ethernet port provides an access connector for plugging in the RJ45 connector that is attached to a network cable.
  • Firewire, also called iLink or IEEE 1394, is used to connect digital camcorders to the PC. There are 2 versions: Firewire 400 that has a DTR of 400 megabits-per-second (Mbps) and Firewire 800 which has a DTR of 800Mbps.
  • Thunderbolt port provides a very high DTR of 10Gbps which allows it to be used as a mini-display port.
  • Portable hard drives can be connected to the computer via the eSATA port. Usually, this port cannot transmit power unless it is a powered eSATA (eSATAp) port.
  • The internal expansion card that allows for audio signals to be processed by the computer is called the audio card or sound card. It allows for input and output of audio signals, and is thus considered an input-output (or I/O) device.
  • An internal expansion card is any device that can be plugged into the expansion slot of the motherboard (informally called MoBo). It is also called a plug-in card.
  • The plug-in card that allows for accelerated rendering of graphics, video processing, and accelerated decoding of video codecs is called a video card or more popularly, a graphics card.
  • There are different types of video display interface in the PC that allows a display device e.g a monitor or TV to be connected to the video source (such as a video card) in the PC. The main types are:
  1. Digital Video Interface (DVI) – Comes as a single link or dual link connector. The single link has 18 pins and a blade, and it supports a resolution of 1920×1200. The dual-link DVI has 24pins and a blade, and supports a resolution of 2560X1600. If it can only transmit digital signals, then it is called DVI-D, but if it can transmit both analog and digital signals, then it is called an integrated DVI or DVI-I. DVI-I has 4 pins – 2 above the blade, and 2 below it, for relaying analogue signals. DVI-D does not have these 4 pins.
  2. High Definition Media Interface (HDMI) – It is designed to carry digital video and audio signals from the video source to a high-definition display device.
  3. Video Graphics Array (VGA) – It is a 15-pin connector that does not carry audio signals.
  4. Component Video – Used to transmit analogue video signals. Like VGA, it cannot carry audio signals. Also, its video signals are split into 3 component channels (color-coded as red, green, and blue). This connector is normally used to connect a DVD player to a television or monitor.
  5. Composite Video – Transmits analogue video signals. Like the component video, it cannot carry audio signals. Unlike component video, the video signal is not split into channels. Its connector is color-coded as yellow.

  • The phono jack is used to transmit analogue audio signals to a headphone or speaker. It is also called an audio jack, jack plug, or headphone jack. It comes in 2 sizes:
  • 3.5millimeter or 1/8-inch jack – The 3.5mm phono jack is the most common type, and it supports stereo audio.
  • 6.35mm or 1/4-inch – Usually used in professional audio equipment such as audio recorders or electronic guitars.
  • The XLR connector is a 3-pin connector used in professional equipment.
  • RCA audio connectors allow for transmission of analogue stereo audio signals to an amplifier or audio receiver.
  • The Toslink connector, also called S/PDIF optical audio connector, is used to carry digital audio signals. It uses fiber optic cable to transmit digital audio data.
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