Docking 101 – First in a Two Part Series

Today's post will be the first in a two part series discussing docking and expansion capabilities for notebook PCs. I want to talk about some of the tradeoffs and design considerations that go into making docks and port replicators. However, first we need to cover some background so that the follow up post makes sense. Those with a Masters or Ph.D. in Docking are more than welcome to guest lecture in the comments. The industry uses the word "docking" as a generic way to describe a device that attaches to your notebook PC which provides a centralized place to plug in cables through one connection on your notebook. Sometimes this is done for convenience – to avoid having to disconnect and reconnect multiple wires each time you sit down at your desk. Other times it is to add ports or functionality that do not exist on the notebook itself. "Docking" for Lenovo notebooks can mean one of multiple options, not all of which are available on every system. In order of increasing complexity and functionality: First is a USB attached port replicator that adds additional USB ports, VGA display output, Ethernet, and some PS/2 ports to the system. It is designed primarily for convenience, as routing all signals through one USB port not only saves USB ports on the notebook itself, but also makes it very easy to connect and disconnect from the system. In addition to ThinkPads, this will also work for our Lenovo 3000 and IdeaPad lines. Theoretically it would also work with a desktop, though I'm not sure why you'd want it to. The advantage of using a USB port replicator is that it is very easy to use and is broadly compatible. The disadvantage is that it is only suitable for basic cable management. Since everything is routed through one USB port, the bandwidth is shared and performance of the peripherals will suffer. This is especially true with video connections, but also applies to Ethernet. Routing a gigabit Ethernet connection through a 400Mb/sec. USB connection that is also carrying video, audio, and other signals isn't exactly high performance computing.

Next up the food chain is our Essential Port Replicator. At this point, all vendors in the industry move away from generic expansion that will work across many systems and into proprietary solutions designed to suit the needs of their specific notebook PCs. In other words, don't expect your Lenovo ThinkPad to plug into a Dell port replicator, and vice versa. Instead of connecting through a USB port, our Advanced Port Replicator uses the ThinkPad docking port found on the bottom of the majority of ThinkPad T, R, and Z series notebooks. It also introduces the concept of "drop in" docking, which means you place your ThinkPad on top of the port replicator and snap it into place. Its overall function and ports are similar to the USB port replicator mentioned above, and its primary mission is cable management – to avoid the hassle of having to disconnect and reconnect power, Ethernet, VGA display, speakers, etc. every time you move away from your desk. Since it connects directly to the system bus, it avoids the performance problems a USB port replicator. Many vendors have their own versions of port replicators under a variety of names.

Stepping up is what is considered by many to be the sweet spot of ThinkPad docking and expansion, our ThinkPad Advanced Mini Dock. This is our best seller overall mainly because it adds significant functionality to the ThinkPad notebooks that support it. These include items like more USB ports, serial port, parallel port, a built in key lock, and most importantly, a DVI port to enable connecting a digital display. Using both the VGA port plus the DVI port, our Advanced Mini Dock can support two simultaneous external displays. It also ships with a second power supply so that you can leave your other power supply in your laptop bag. Again, this level of port replicator is a common item for a vendor to have as an option for its business systems.

The grand daddy of all expansion is called "full docking." We call our version the ThinkPad Advanced Dock. At this level, it is common to add a few additional ports, but a full dock really exists to add an optical drive/HDD expansion bay and/or a PCI Express graphics slot. This graphics slot will allow a dedicated graphics card to be added so that a system can drive more than two simultaneous displays. Only a few vendors offer a full sized dock, as many see it as an anachronism of a bygone era.

One of the versions above usually works well with full sized notebooks, but ultraportable notebooks (12" displays or smaller) are a totally different story. Notebook vendors are split as to how they address docking for their smallest notebooks. There are three options, each with its own benefits and tradeoffs:

  1. Add support for the same port replicators and docks that bigger cousins in the vendor's lineup use (known as common docking).
  2. Provide a dedicated way to expand that is optimized for the smaller sized notebook. We do on our X Series notebooks and tablets with the ThinkPad X series Media Slices.
  3. Eschew docking completely – only support USB port replicators. Another option just emerging in the industry is wireless docking. This is how we address expansion for our ThinkPad X300. (More on wireless docking in the follow up post).

Option one, adding support for the same docks and port replicators that bigger systems use, seems perfect. Customers who use "hot desking" love this compatibility. Hot desking is often used in sales or other environments when users are commonly away from the office. Instead of giving each person a dedicated desk, users can drop in to the office once every so often, find an empty desk, and then sit down and work. This saves real estate space since on average only a small percentage of people will come by the office to work. Companies who use hot desking love common docking because it allows them to set up a standardized work environment with external display, keyboard, mouse, and Ethernet connection all connected to a port replicator or dock. Regardless of whether a user uses an ultraportable notebook or a full sized notebook, the company does not have to worry about having to supply different docks and port replicators.

While this seems like the obvious solution to implement, it has a significant tradeoff – adding support for common docking adds considerable thickness and weight to a notebook. Ultraportable users are extremely conscious about both of these, and are often unwilling to add to system bulk to get common docking with the rest of the family lineup. Since the ultraportable range is the most highly contested (though not the biggest volume) area of notebook design, being even a few ounces or tenths of a kg heavier or thicker can dramatically impact sales.

Option two involves creating a dedicated "expansion base" for the smallest ultraportable systems. This is the option most often chosen by system designers. Our ThinkPad X series Media Slice is one example of this category. By being optimized for one particular notebook family, it can be made small, portable, and also address any shortcomings not available on the main product. For example, we use our Media Base to add support for an Ultrabay optical drive, DVI, and a few more USB ports. Since the design is small and light, it is versatile enough to be portable. Admittedly though, few people actually carry it around with them. For those people who leave it behind, we also provide a key lock to lock the notebook in place when it is on the user's desk for more security.

Option three is to simply not provide a connector for docking at all. A few months ago, this meant a user would only be able to use a USB port replicator. However, with the availability of Ultra-Wideband technology (UWB), wireless docking is just becoming a possibility. Unfortunately though, it is no panacea either. More on that in the next post. I hope this post has laid the groundwork for some more advanced discussion next time. In the next post, Docking 201, we'll explore the following topics: Tradeoffs in designing docks, usability considerations, advanced video support, wireless docking, the future of docking, and more (your suggestions welcome). That's when the real fun begins. For now, we are actively soliciting feedback and opinions on future docking possibilities. If you would be willing to provide some feedback by participating in this survey, our team would be very interested what you have to say. We will not use your information for marketing purposes (i.e. sell you out). Here's the link.