A Brief History of USB and Docking Stations

In the Beginning

The history of docking stations starts at the dawn of the personal laptop computer and the constant desire to increase productivity. One method of doing so was by using a docking station in order to connect multiple external devices, such as an external monitor and a full-size keyboard.

However, in the early days of personal computing, docking stations were:

• Mechanical
• Proprietary
• Expensive
• Bulky
• Limited in terms of the number of external displays
• Needed to be replaced when you switched computer models

The Introduction of USB and Indirect Display Technology

The introduction of the Universal Serial Bus (USB) and the evolution of USB to higher data transfer speeds afforded by USB 2.0 and USB 3.0 allowed for expansion capabilities not previously possible.

One outcome of this capability was the invention of  ‘indirect’ display technologies that allowed a video signal to be transmitted via a USB data-only connection.

‘Indirect display’ technology refers to any device that allows a display to be connected to the host without being directly connected to the graphics processing unit (GPU), and there are several different types of indirect display technologies available:

• DisplayLink
• Silicon Motion
• MCT Trigger

Technologies such as DisplayLink are, in essence, a ‘virtual’ graphics processing unit that relies on the host system’s internal CPU and ‘physical’ graphics processing unit (GPU) in order to generate the image shown on the displays.

Because technologies such as DisplayLink use a USB data-only connection, they provide a universal solution via a USB cable as opposed to the physical and proprietary connection used by older ‘mechanical’ style docking stations. 

An example of a universal solution is the Plugable UD-3900 docking station. Over its twelve years on the market and hundreds of thousands of units sold (and still going strong), it has enabled increased productivity by allowing two additional displays, six USB ports, wired Ethernet connectivity, and audio input and output. 

USB Type-C and Thunderbolt (1, 2, 3, 4 & 5) and USB4

USB Type-C

The availability of computers with USB Type-C in March of 2015 and computers with Thunderbolt 3 in December of 2015 provided options for expansion that were previously unavailable via USB 2.0 and USB 3.0.

The primary capabilities of both technologies were additional video outputs and the ability to charge the host computer via a new method called USB Power Delivery (USB PD). 

With the introduction of USB Type-C, there were revolutionary changes as composed to the original USB Type-A standard (i.e. USB 2.0 and 3.0):

• The physical port type changed (symmetrical and smaller)
• The bandwidth of the connection increased
• More power was available to external devices
• For the first time, power could also be ingested (USB Power Delivery)
• The ability to output a single video signal was added (VESA Alt Mode video)

The introduction of USB Type-C and its new capabilities prompted Plugable to introduce its first ‘hybrid’ docking station, the UD-ULTCDL which combined USB Type-C technology with DisplayLink technology. It allowed for three external displays, host computer charging, and a plethora of additional peripherals. 

Thunderbolt (1, 2, 3, 4 & 5)

Thunderbolt is an interface standard jointly developed by Apple and Intel that sought to provide a single way to connect just about any kind of external device to a personal computer. 

First introduced in 2011, as of the spring of 2025, Thunderbolt has gone through five major revisions (Thunderbolt 1, 2, 3, 4, & 5) and each major revision followed a similar path as USB, in that each new version provided improvements over their predecessors. 

Thunderbolt 1 and Thunderbolt 2 used a mini-DisplayPort connector, and provided high bandwidth data transfer and a single video output. The evolution between the two was primarily the bandwidth of the connection (10Gbps to 20Gbps).

Thunderbolt 3 was a revolution, in that it was the first to adopt the USB Type-C connector. This allowed any Thunderbolt 3 port to be backward compatible with a USB Type-C device, while at the same time superseding USB-C’s capabilities.

In essence, a Thunderbolt 3 connection is a direct connection (tunnel) to the host’s internal PCI Express bus, and provides up to 40Gbps of data bandwidth between the host and device. This in turn allowed for capabilities not seen before:

• Provides up to 40Gbps of data bandwidth between the host and device (may only offer 20Gbps). 
• Can optionally support up to two external video outputs, each supporting 4K@60Hz
• Can provide up to 15W of power to external devices, as well as optionally support USB Power Delivery to charge the host
• Supports daisy-chaining of devices together in a serial connection format (the devices must support this feature)

The introduction of Thunderbolt 3 and its new capabilities prompted Plugable to introduce a variety of Thunderbolt 3 docking stations, such as the TBT3-UDV and TBT3-UDZ, each offering dual 4K display support along with high-speed device connectivity. 

Released in 2020, Thunderbolt 4 was an evolution in terms of Thunderbolt’s overall capabilities:

• Any host port labelled Thunderbolt 4 MUST support two external displays 
• Any host port labelled Thunderbolt 4 MUST support 40Gbps of data bandwidth
• Most (but not all) Thunderbolt 4 hosts support USB power delivery up to and between 100W to 140W (workstation or gaming class laptops with higher power requirements are typically excluded)
• Thunderbolt 4 introduces support for a hub device topology as opposed to the serial device (or daisy chain) topology present in Thunderbolt 3

The introduction of Thunderbolt 4 and its new capabilities prompted Plugable to introduce a variety of Thunderbolt 4 docking stations such as the TBT4-UDZ, TBT4-UD5, and TBT4-UDX1 once again raising the bar for expandability and performance.  

Devices based on Thunderbolt 5 became available in late 2024 (for example the Apple Mac mini with an M4 Pro processor), and the latest version of the standard once again offered performance improvements as compared to its predecessor:

• Up to 80Gbps symmetrical bandwidth, dynamically changing to 120Gbps/40Gbps asymmetrical for enhanced video performance when needed
• Up to 140W charging in most cases, optional up to 240W
• Higher display refresh rates (up to 540Hz) and a greater number of displays (optionally up to three 4K at 144Hz)
• Backward compatible with Thunderbolt 4, Thunderbolt 3, and USB-C (the ‘do everything port’)

Without giving too much away, Plugable Thunderbolt 5 docking station products are in the works and will be available in 2025, which will once again demonstrate Plugable’s leadership in the computer docking station market. 

USB4

USB4 is the next evolution of the USB Type-C standard and is meant to provide performance upgrades (to between 40Gbps & 80Gbps) in an effort to match, or in some cases, exceed those of Thunderbolt 3 or Thunderbolt 4 (but not Thunderbolt 5).

USB4 hosts can optionally support Thunderbolt 3, however, Microsoft requires that a USB4 host also supports Thunderbolt 3 in order to receive Windows certification.

The USB4 standard is supported by several Plugable products, most notably the USB4-HUB3A hub, which allows for multiple USB4 and Thunderbolt devices to be connected to the host computer, in addition to supporting up to two additional displays. 

To Summerize

The last few decades have seen incredible progress regarding computer expandability. Despite the progress, there is not one single solution appropriate for everyone. 

From its beginnings in 2009, Plugable has recognized this fact and has offered a variety of solutions based on USB, DisplayLink, USB Type-C, Thunderbolt, and USB4 in order to meet the varying needs of almost any personal computer user. 

This understanding, along with our mantra of Better Products, Better Information, Better Support will allow Plugable to continue to offer broadly compatible products, making use of the latest technology to increase personal computer productivity for many years to come.