What is ghosting and antighosting, anyway?
According to Antighosting Explained: "Some keyboard keys don’t work when multiple keys are pressed simultaneously. The key presses that don’t show up on the computer or seem to have disappeared are said to have been ghosted. On most keyboards, even some that are explicitly marketed as Anti-Ghosting, this happens with many three key combinations.
Want to know if your own computer keyboard will work with Plover? Test its antighosting abilities online with the Keyboard Ghosting Demo. As far as I know, the only true antighosting keyboards on the market are the SideWinder X4, Razer Tarantula, Stealth 7G, and Logitech G19. The SideWinder is by far the cheapest of these, but if you have one of the others lying around, you should give Plover a try.
The Sidewinder FAQ states that the X4 can recognize up to 17 alphanumeric keypresses at a time. But a steno machine has 22 keys, and all of them can theoretically be pressed at a time! I was worried that this might be a problem, but then I looked in my actual steno dictionary, and noticed that the longest single stroke (STKPWHRAOEUPBS, an alternate stroke for "guidelines") only used 14 keys. So maybe there are some people out there whose dictionaries contain lots of 18-to-22-key strokes, in which case they'll probably have to upgrade to the more expensive antighosting keyboards. If you're like me, and your steno dictionary stroke length maxes out at 17 or fewer, you're probably okay.
True antighosting is paramount when using a qwerty keyboard as a steno machine. After a few weeks with the SideWinder X4, I'm happy to report that its key recognition capabilities seem to be flawless. For a $60 keyboard, that's no mean feat. I can't recommend it highly enough. Microsoft isn't giving me any kickbacks, either.