Hardware

Ports and Interfaces

One commonly confused concept in IT is the difference between an interface and a port. You will often hear these terms used interchangeably, but there is a difference. An interface is how a device communicates. For example, a mouse is a hardware interface. In particular, it is an input interface. The mouse lets the user send x and y coordinates to the operating system to move the cursor around the screen. Consequently, the mouse is a hardware interface that is also an input interface. How it connects to the computer is through a port.

The mouse also communicates with a software interface called a driver. The driver is software that translates the raw input from the hardware to the operating system. It can also translate output from the operating system to the hardware (think of an image being displayed on your monitor).

A port is often the physical connection to the computer. Most mice in the past decade are USB. The USB is the port that the mouse uses to connect to the computer. The physical port is what transfers the electrical signals back and forth. To clarify, the mouse is a hardware input interface that sends x and y coordinates to the operating system through the software interface of a driver so that the operating system can understand the data being fed to it. The mouse itself is plugged into a USB port. The USB port itself is capable of inputting and outputting data—think of a flash drive—but is only inputting data from the mouse.

Video Ports

Video ports are just what they sound like—ports that output video. Before we delve into the various video ports every IT technician should know, it is important to know the difference between analog and digital video signals. An analog video signal is presented in a waveform, whereas a digital video signal is discrete binary bits of 0 or 1 (see Figure 2-4).

Figure 2.4 Analog vs. Digital Signal

Binary is how computers function and dates back to early circuits. A circuit was either open, or off (0), or it was closed, or on (1). If you look on a PSU, you will see a switch with a 0 and a 1. Zero means off, and one means on. Early video ports were analog, so if the monitor received analog signals, the computer would have to convert from binary to analog for the monitor to understand it. Today, most monitors are digital, so the move from analog to digital makes sense.

HDMI

High-Definition Multimedia Interface, or HDMI, ports are one of the most common video ports for both televisions and monitors. It is a digital port consisting of 19 pins that can transmit both audio and video. With the introduction of the HDMI 2.1 standard, an HDMI 2.1 port can support 4k, 5k, 8k, and 10k at 120 Hz and 48 gigabits per second (Gbps) of bandwidth/data. This is a huge improvement from the previous HDMI standard, which could only support up to 4k at 60 Hz. The two most common HDMI ports are standard (Type A) and Mini (Type C, not to be confused with USB C). See Figure 2-5.

Figure 2.5 Mini HDMI (on Left) and Standard HDMI (on Right)

DisplayPort

DisplayPort is a popular digital, 20-pin, video port that many gamers prefer over HDMI. It supports both video and audio like HDMI. While it has never really gained traction in the television space, it is fairly common on modern video cards and monitors. It can output, on the high end, 8k at 240 Hz with 77.37 Gbps of bandwidth/data! For some, it is easy to confuse a DisplayPort and an HDMI port because one side looks identical to the other. However, a DisplayPort has a flat end on one side. There is also a mini DisplayPort that looks quite different. See Figure 2-6.

Figure 2.6 DisplayPort and Mini DisplayPort Illustration

DVI

A DVI is an older 24-pin port that can be both digital and analog and carries only video and not audio. Unfortunately, marketing of this port made it more confusing for consumers. There are several variations of DVI: DVI-D Single Link, DVI-D Dual Link, DVI-I Single Link, DVI-I Dual Link, and DVI-A. DVI-A was pure analog and is not used anymore. However, you will still see DVI-D and DVI-I in some older computers. DVI-D is a pure digital connection. It is capable of a max resolution of 3840×2400 at 30 Hz in Dual Link. You will still see people use DVI-D today because it can display 1080p at 144 Hz, but you would have to have a separate audio cable. See Figure 2-7 to see what a DVI-D looks like.

Figure 2.7 DVI-D Cable

DVI-I is another port you might still see. It is capable of carrying an analog and a digital signal on separate pins. It does not convert digital to analog signals or vice versa. Rather, it can pass through analog signals on certain pins and digital signals on other pins. This is important because you can’t plug a DVI-A or DVI-I cable into a DVI-D port, but you can plug a DVI-D cable into a DVI-I port. See Figure 2-8 to see a DVI-I port. Notice the cross formation with four dots around it. Those four dots are for analog signals.

Figure 2.8 DVI-I Port

VGA

A VGA cable is a 15-pin analog port. It does not carry audio signals much like DVI. VGA is one of the original video ports. While it can display up to 2048×1536 at 85 Hz, it is not considered a high-definition port. This means you can display 1920×1080 at 60 Hz, but it will be an analog signal and HD is a digital signal. Component ports are the only analog ports that are capable of being called HD because they still carry a digital signal over the analog communication. VGA would have to convert the digital signal to analog and, consequently, is not labeled as true HD. In fact, if you were to compare an HDMI display at 1920×1080 to a VGA display at 1920×1080, you would notice that the VGA display is fuzzier and not as crisp. VGA cables are often blue (see Figure 2-9) but can come in other colors.

Figure 2.9 Traditional Blue VGA Cable

USB-C

USB-C can carry audio and video. However, it can do more than that. USB-C, while a port, is also a form factor. This means that it’s one of the more complicated concepts for consumers. See the subsection “USB-C” later for more information.

USB

Universal Serial Bus, or USB, is a common port type found in most computers today. By design, it can transmit both power and data. The serial in its name is an important distinction because it is an evolution of the original 9-pin serial port, also called an RS-232 port. While serial ports have all but disappeared from modern computers, they are still in use in industrial control systems and commercial routers and switches. While serial ports are slow in data transfer and do not support power over their wires like USB, they are reliable and easily programmed. Luckily, while most modern computers do not include serial ports anymore, there are many serial-to-USB adapters on the market to communicate with serial port devices. Some people confuse serial ports with VGA ports because of the similar external design, but there are two ways to identify them easily. First, serial ports have only 9 pins, whereas VGA ports have 15 pins. Also, most serial ports are male (pins sticking out), whereas most VGA ports are female (holes for the male pins on the cable to plug in to). In other words, serial ports are male and their cables are female, whereas VGA ports are female and their cables are male. See Figure 2-10 to see a serial port next to a VGA port on the rear input/output panel of a motherboard.

Figure 2.10 Directly Below the Large Pink Parallel Port Is a Serial Port (Left) and a Blue VGA Port (Right)

USB speeds have dramatically improved over the years. The first USB version, USB 1.0, was capable of 1.5 megabits per second (Mbps); USB 1.1, 12 Mbps; USB 2.0, 480 Mbps; USB 3.0, 5 gigabits per second (Gbps); USB 3.1, 10 Gbps; USB 3.2, 20 Gbps; USB 4, 40 Gbps; and USB 4 2.0, 80 Gbps.

USB Form Factors

In addition to the different USB versions, which primarily affect speed, there are also different USB form factors. Consequently, USBs can look different from each other. Traditionally, when most consumers think USB, they are thinking of USB-A. This is the original rectangular port that has a singular orientation, which means you can only plug it in one way. USB-B is more square and has been traditionally used to connect to printers and is now a popular connection to 3D printers. Mini-USB was a popular standard for phones and portable electronic devices for some time before micro-USB replaced it. Both are singular orientation, and the plug can only be plugged in one way. The newer form factor that has been gaining rapid momentum is USB-C. USB-C is not singular orientation and can be plugged in right side up or upside down. It is now becoming common on most electronic devices, including phones. In addition to the ease of plugging in, there are a multitude of other benefits to USB-C. See the following section for more information. Figure 2-11 helps you visualize the different USB form factors.

Figure 2.11 USB Form Factors

USB-C

USB-C is fast becoming the most ubiquitous of USB form factors. It is also one of the more complicated form factors. By definition, USB-C can carry data and power like the original USB standard. It is now being used as the favored port to power many laptops out there. However, it is also capable of carrying video and audio. Its bidirectional method of plugging in—so you don’t have to worry about which side is up—and smaller footprint have made this a prolific form factor. However, the capabilities of USB-C vary wildly and depend on the actual interface technology being used behind the form factor.

USB 3.0, capable of 5 Gbps, can be a USB Type A or USB Type C form factor. USB 3.1, capable of 10 Gbps, can also be Type A or C. However, USB 3.2 is almost exclusively USB Type C, which is capable of 20 Gbps. How do you know which USB type your USB-C port is? Read the documentation for the specific electronic component that has the USB-C connection.

To add to the complexity, USB 4 is often called Thunderbolt, but technically Thunderbolt 3/4 is one proprietary implementation of USB 3.1/4 capable of 40 Gbps. Non-Thunderbolt USB 4 is only capable of 20 Gbps. Thunderbolt 5 uses USB-C as well and is capable of 80 Gbps. So, all Thunderbolt 3/4/5 interfaces are USB-C ports, but not all USB-C ports are Thunderbolt. Again, how do you know if you have a regular USB-C port or a Thunderbolt USB-C port? Read the documentation or look for the proprietary lightning bolt icon next to the port. See Figure 2-12.

Figure 2.12 Thunderbolt USB-C Port (Look for a Lightning Bolt by the Port)

Ethernet Ports

The most common interface for an Ethernet port is an RJ-45 connector (see Figure 2-13) plugged into a network interface card (NIC). The Ethernet port on the NIC is what you would use to physically connect the Ethernet cable to the Internet or local network. If you connect wirelessly, you use a wireless NIC, and no physical cable is needed. There are also fiber connections to connect to networks, but they are typically not found as direct connections to consumer devices at this time.

Figure 2.13 RJ-45 Connector (Wider and Has More Wires Than the Older Telephone Connector, Which Was an RJ-11)

An Ethernet cable to connect to a network might be called a CAT 5e, UTP, 1000BASE-T cable with an RJ-45 connector. Let’s break this down:

• An Ethernet cable is often categorized as a CAT cable, with CAT abbreviated from Category. There are currently eight categories of Ethernet cables: CAT 1–5 are rarely used anymore; CAT 5e and 6/6a are commonly used, and CAT 7/8 are used for short runs in data centers. The higher the category, the faster the Ethernet cables can transfer the data. This explanation is a tad oversimplistic but helps in the general overview. CAT 5e is still used in many places and is capable of delivering 1 Gbps of data. CAT 6a can deliver 10 Gbps of data. Both CAT 5e and CAT 6 are capable of sending data 100 meters before needing a signal repeater. CAT 7/8 can deliver 40 Gbps of data but only between 10 and 30 meters and are typically used only in data centers.

• The TP stands for twisted pair. Starting with CAT 3, electrical engineers started twisting the wires together to reduce electrical interference. Now, we have eight wires twisted in four pairs to reduce interference and gain speed (see Figure 2-14). When cutting your own Ethernet wiring, you must untwist the ends of these wires to slide them into an RJ-45 connector. In addition to TP, which all Ethernet cabling uses now, you can also purchase STP or UTP. Both are twisted pair, but U stands for unshielded and S stands for shielded.

  

  Figure 2.14 Twisted Pairs in Ethernet

  • Unshielded is what it sounds like. The cable is unshielded from any sort of electromagnetic interference. The cables are generally cheaper and more flexible than shielded cables. For most smaller runs inside a home or office, UTP is acceptable.

  • Shielded twisted pair means the cable itself is made of a material to help protect against electromagnetic interference. It is often made of PVC or plenum. Plenum is often required if running Ethernet in walls because it has flame-retardant properties. Often the individual wires will also have a foil shielding to protect against interference. STP is often used in commercial projects or for long runs. However, STP is usually more expensive than STP and not as flexible.

• PVC is polyvinyl chloride, which can produce toxic fumes and should be used in open-air situations.

• Plenum cables have a fire-resistant jacket and should be used inside walls, drop ceilings, or under raised floors.

• The 1000BASE-T part means that there is 1000 Mbps of bandwidth. You will also see this written as 1GBASE as well. The G stands for gigabit, which is equal to 1000 megabits. The BASE merely refers to baseband signaling, which means only Ethernet signals are carried on it. The T stands for twisted pair. Yes, this is redundant because the T in UTP and STP also stands for twisted pair.

Common Power Cables (Desktop, Laptop, Mobile)

Most desktop computers use a C13 power cord on one end and a country-specific plug on the other end. This cord then connects to the computer’s PSU. This common cable allows for easy shipping to many countries because the C13 is a universal standard and readily matched with the correct country-specific plug on the other end (see Figure 2-15). Some computer manufacturers use a proprietary power adapter, but it is rare in the desktop marketplace. The power cable will go from the wall directly to the PSU the majority of the time. The PSU will then convert the AC electricity from the wall outlet to DC electricity for the computer to run.

Figure 2.15 Typical Desktop Power Cable with C13 Plug (Left) and Country-Specific Plug (Right)

Unfortunately, for many decades, laptops have used proprietary power adapters. There are dozens of proprietary charging tips/types for different manufacturers. Even the same manufacturer often has different charging tips/types for different models. To make it even more confusing, even if two laptops have the same charging tip, that doesn’t mean you can use one charging cable on the other because often it has different voltage and amperage output. Luckily, because of the USB-C’s capability to carry enough power to power many laptops, we are starting to see an adoption of that universal standard.

Like laptops, mobile phones have had a litany of various power cables. There are dozens of proprietary phone cables. Most notably was Apple’s Lightning cable, which was the follow-up to the company’s proprietary 30-pin connector in use previously. Luckily, with the introduction of the iPhone 15, Apple has moved to the universal standard of USB-C. Most phones out now use USB-C. There are still some proprietary cables out there, but they are fewer than before. Before USB-C, phones started out with almost entirely proprietary adapters, then moved to mini-USB, then micro-USB (refer to Figure 2-11).

Converters vs. Adapters

One important distinction when needing to convert from one type of cable to another is whether you need a converter or an adapter. An adapter changes the plug type but must be the same signal. For example, you can go from an HDMI plug on one side to a DisplayPort plug on the other side with an adapter. They are both digital signals, so you are just adapting one plug to the other.

However, you will need a converter if going from a digital signal to an analog signal or vice versa. For instance, if you want to go from VGA (analog) to HDMI (digital), you will need a converter. Converters require power and are often more expensive than adapters. There are unscrupulous people on the Internet who will sell you an HDMI-to-VGA adapter where they just rewire the pins to each other. However, it will not work because you can’t just send an analog signal to a digital signal without first converting it.