Exam Spotlight: a look at Display Connectors 

Relevant Exam – CompTIA A+ 220-901

Back in the day, computers were plugged into these beige TV boxes with glass screens and cathode ray tubes, commonly referred to as monitors. Computer monitors varied in size and resolution, and all of them had the relative weight of a dying star. Monitors often developed a high-frequency whine that could send dogs into a howling frenzy. They sometimes ran hotter than the PCs they were hooked up to. And, if you tried to service a monitor yourself, you risked electrocution even if it wasn’t plugged into a wall socket (see: capacitors).

Modern computer displays are thin, light, and power efficient. They have very fast response rates, broad color palettes, and remarkable high-resolution capabilities enabled by pixels that keep shrinking with each new generation of display.

The previously mentioned prehistoric monitors were almost entirely standardized on a single connector, and for an astonishing number of years. This connector is still out in the wild, and is actually installed on many current models of desktop and laptop computers.

Time and technology have added new connectors to the mix, in order to take advantage of more powerful graphics processing units (GPUs) and more advanced displays. Anyone taking the CompTIA A+ hardware exam 220-901 should be able to identify the following different display connectors, and know the differences between them.

Video Graphics Adaptor (VGA)

VGA has been around since dinosaurs used computers to play Lemonade Stand. VGA connectors use 15 pins configured in three rows of five pins. The male connector usually includes two screws connected to plastic pegs—these are used to securely attach the connector to a graphics card’s VGA port. The pegs are slotted so they can be tightened with a flathead screwdriver, but hand tightening works just as well.

VGA male connector with screws

VGA port with sockets for connector screws

A VGA connector is sometimes referred to as a “DE-15” or “D-sub 15” connector, as the socket is “D” shaped when turned sideways.

A significant difference between VGA and other formats is that VGA uses an analog signal to transmit video data, where newer formats employ digital signals.

VGA was a popular standard for many years, which is why displays using VGA connectors are still commonly found in offices and other businesses. This is why many current laptop models still have a VGA port, even though it is an old standard that is slowly being phased out.

Digital Video Interface (DVI)

DVI was introduced as the potential successor for the VGA standard. Instead, DVI and VGA have co-existed side by side for several years.

There are three primary types of DVI connectors:

  • DVI-D (Digital signals only)
  • DVI-A (Analog signals only; useful for older displays)
  • DVI-I (Integrated; can send analog or digital signals according to what the display supports)

In addition, DVI comes in single-link and dual-link formats. DVI single-link supports resolutions up to 1920×1080, while DVI dual-link supports resolutions up to 2560×1600 (with a graphics card that supports DVI dual-link.)

DVI connectors can use up to 24 pins arrayed in three rows of eight pins each, alongside a 5-pin block in which one of the pins is a horizontal blade. Like VGA, DVI connectors usually have two screws used to secure the connector to the port.

DVI connectors: analog, digital, integrated

High Definition Multimedia Interface (HDMI)

HDMI has become the de facto standard for home entertainment components. Disc players, videogame consoles, cable receivers, and streaming boxes all employ HDMI connections, usually to large screen televisions equipped with multiple HDMI ports.

HDMI has also become a popular way to connect PCs to big screen TVs and computer displays. Most modern desktop PCs and laptops come equipped with HDMI ports.

HDMI connector with 19 pins

A key defining characteristic of HDMI is that it transfers both video and audio data across a single connection.

The first version of HDMI (1.0) supported a max resolution of 1920×1080 at 60Hz, the same resolution as a Blu-ray video disc and most big screen televisions. This is still the most common resolution used with an HDMI connection, although the adoption of 4K displays could eventually bump this number up.

Further releases of HDMI have increased the max resolutions supported. HDMI 1.3 increased it to 2560×1600 at 60Hz. HDMI 1.4, released in 2009, offers a max resolution of 4096×2160 at 30Hz. HDMI 2.0 improved the 4096×2160 resolution refresh rate to 60Hz.

HDMI 2.1 is currently under development, with no set release date.

DisplayPort

DisplayPort is a growing in popularity display connector which supports very high resolutions. DisplayPort is commonly used with 4K computer displays using a resolution of 3840×2160 at 60Hz.

DisplayPort is also being touted as the standard display connector for upcoming 5K and 8K displays, although these products are still very much under development.

DisplayPort 20-pin connector

DisplayPort is unique in that multiple displays can be daisy-chained together, either through dual onboard ports on the displays or via a DisplayPort hub. This ability lets a PC’s single DisplayPort plug connect to several displays at once. The larger the number of displays, the lower the max resolution setting is for each display.

Most laptops equipped with DisplayPort support use a smaller version of the connector, called Mini DisplayPort. In this case, a cable with a Mini DisplayPort connector on one end and a regular DisplayPort connector on the other end is used to connect a laptop to an external display.

Mini DisplayPort port on a laptop

Thunderbolt

Thunderbolt was developed by Intel and Apple as an alternative to DisplayPort. It is not purely a display connector standard, as Thunderbolt can also be used to connect devices to a PC. It does so by implementing a PCI Express (PCIe) signal on the same cable as the display data.

Like DisplayPort, Thunderbolt can be used to daisy-chain a number of displays to a single port. Thunderbolt adds the ability to add devices like external hard drives and RAID arrays to the chain of displays.

The first two versions of Thunderbolt used a connector that was physically the same as a Mini DisplayPort. The latest version, Thunderbolt 3, uses the same connector as the new USB Type-C standard. This new USB connector is slowly gaining traction in the industry, but it still has a long way to go.

Posted on 29th September 2016 in Blog, Featured Article
 

Comments are closed.