Founded by refugees from HP in the mid-1970s. Famous for the NonStop line of fault-tolerant computers. Every part of the machine - disk, power supply, bus, processors, you name it - was hot swappable. If any part failed you just yanked it out and dropped in a replacement, all with the machine online. The machines had multiple processors, typically 4, working in (oddly enough) tandem. A process would run 'live' on one processor but keep a backup of itself which could take over seamlessly if the first processor failed. This backup process could be on another processor of the same machine, but was more frequently on another remote machine. The backup methodology was called checkpointing.

These machines were used by banks and other financial institutions for processing critical transaction-based data. The Canadian banks headquartered in Toronto (all within blocks of each other) all had primary Tandem machines in their subterranean datacenters, and the remote paired machines lived in their secret twin data centres in Markham - all, also, within blocks of each other.

I used the Tandem TNS-II in the mid-80s, programming in TAL to the original Guardian OS. It was a lot of fun! Screens were written in SNOBOL which was less fun, but I was writing the back end so that was somebody else's problem.
Also a bicycle built for two. The front rider is called the captain the rear rider is the stoker.

A tandem allows two people of differing bicycling skills to stay together. A tandem is faster than a single; tandems go like a bat out of hell on downhills. They are also faster on the flats, but are slower going uphill. They are also more stable than singles, but this also makes them less responsive. When riding a tandem you can't make the kind of last second changes in direction that you can make on a single.

Tandems are expensive; a good tandem can cost more than twice as much as a good single of the same quality. A tandem is for two people, and both of you should be involved in the selection. When you are ready to buy a tandem take the time to find a shop that has experience selling tandems. A good bike shop may not be a good tandem shop. Look for a place with several tandems on display, and one that carries several different brands. See if you can get an extended test ride. It is harder to fit two riders to a tandem than it is to fit a single rider to a single bike. Do not settle for anything less than a perfect fit for the both of you. If you do you may end up riding that tandem alone. Having enough room for the stoker is especially important. Consider getting a suspended stoker seatpost, even if the captain does not have one, because the stoker’s ride is harsher.

You may want to get a used tandem as your first tandem, you can save some money and get the experience you need to make an informed choice, when you get your perfect tandem. Some good websites for used tandems are the Tandem Club of America:, and Tandem Magazine: So go shopping and find a tandem both of you are comfortable with, then check the websites for a good used version of the same bike.

Bikes often appeal to the gearhead in us, tandem also do, but even more so; there is just so much more to tinker with in a tandem. So have fun.

One possible way to go skydiving.

You are linked to your instructor (generally with your instructor strapped to you much like a backpack) throughout the entire jump, so that he or she is in complete control, leaving you to sit back and enjoy the view.

In my opinion Tandem makes a first skydive much easier - seven hours less of class, and if you chicken out someone else will pull the rip cord for you.


A two-wheeled chaise, buggy, or noddy, drawn by two horses, one before the other: that is, at length.

The 1811 Dictionary of the Vulgar Tongue.

Tan"dem (?), adv. & a. [L. tandem at length (of time only), punningly taken as meaning, lengthwise.]

One after another; -- said especially of horses harnessed and driven one before another, instead of abreast.


© Webster 1913

Tan"dem, n.

A team of horses harnessed one before the other. "He drove tandems." Thackeray.

Tandem engine, a compound steam engine having two or more steam cylinders in the same axis, close to one another. --
Tandem bicycle or tricycle, one for two persons in which one rider sits before the other.


© Webster 1913

Tan"dem, n.

A tandem bicycle or other vehicle.


© Webster 1913

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