First, it has an extra top row of PF key’s above the function keys. This top row is programmable on the keyboard itself; no special drivers or software. Some other vintage programmable keyboards also have extra keys, but they are on the left side of the keyboard which makes the keyboard too long for most keyboard trays. Other programmable keyboards require computer software or drivers to work, which means that if the company stops supporting the product, the keyboard will become obsolete. I couldn’t do without these PF keys for my CAD work.
Second, it has a built-in calculator that can send results directly to the computer. This is a function that is unique to an extremely few number of keyboards. I think there’s a patent on it or sumfin, otherwise I’m sure this would be a more common feature. As it stands, only two Focus keyboards and a few their predecessor Omni keyboards have this feature; and only the Focus keyboards have the “Send” function.
Once a person gets to using this features, they become addicted to them.
The fact that makes all of this frustrating is that no new FK-8200’s have been made in several years, and the company that used to make them appears to no longer be in business. Finding these keyboards is becoming increasing more difficult as time goes by. I’m becoming dismayed at the prospect of breaking mine and not being able to find another to replace. They are good quality keyboards that take frequent use in stride, unless you happen to spill the slightest bit of liquid on it, then they fry. I’ve already destroyed two this way.
[UPDATE April 2024]
So this article gets a far amount of attention from time to time. There seems to be interest in the feel of the FK-8200, its programmable keys and also the calculator function. As noted in the comments, I'm also using a G910 keyboard, which has a mechanical-feel keyboard and nine programmable keys. It works well, though software is needed for the programmable keys. Additionally, I'm considering something like a modern numeric keypad that doubles as a calculator, which appears to have a function to send calculated values to your computer, similar to the FK-8200.