by Alan Kamrowski II, June 2006
The original version of this keyboard encoder was reviewed by Retroblast back in May, 2005. It didn’t fare very well in its original review as it had serious ghosting issues. We are happy to report in this review that these issues have been resolved because the encoder has been redesigned to contain built in diodes which eliminate the issue. You can clearly see the added diodes between the connector and the IC in the new style board below on the right:
Here is a run down of the encoder’s features:
The first thing that struck me when I saw the encoder is that it looks to be of good quality. The board is clean and nice and looks professional. The documentation available at www.toknmedia.com for this board is also very detailed and is a great resource on how to get the board up and running.
It ships with a 6 foot PS/2 keyboard cable to connect it to your PC’s PS/2 keyboard port. You will need to obtain a floppy drive cable to hack into your wiring however.
I created a test panel with a little bit of scrap wood and some cutting and drilling. It isn’t a work of beauty by any means, but should suffice for testing keyboard encoders! It had more buttons, but I couldn’t leave my main cabinet without its buttons for too long!
The wiring proved the most difficult part of doing this review because you need to use a PC Floppy cable. You need to cut off one end and separate all the wires in pairs. The small gauge wiring is not very forgiving and even just a little too much pressure with the wire strippers and you’ll cut the wire off very easily. Here is the one I hacked:
I ended up connecting the wires to the microswitches using paper clips. Not the most elegant solution, but short of soldering or crimping on some connectors, it worked great for my test panel.
The KB16 also provides for a remote diagnostic LED via the floppy header. I tested this and it work well, lighting the LED exactly the same as the on board diagnostic LED. It is important to understand that this remote LED is not a numlock, capslock, or scrolllock LED, it is for displaying diagnostic info.
I found the KB16 very easy to use. Programming was easy--you just need to connect a keyboard and press the scroll lock key to enter programming mode. After that you just need to hold down the arcade button (input on the KB16) and the key you want it to produce on the passthrough keyboard. You will see the diagnostic LED light up solid to indicate that it accepted the key. The one downside to programming is that there is no way to exit programming mode without disconnecting the KB16 or powering off. The instructions say something about unplugging the KB16 from the PC, but since PS/2 ports are not technically hot pluggable, you really should power off and then unplug the power cord from the PC to make sure they keyboard interface is off.
I tested all the inputs, and the KB16 has no problem reporting them all at the same time, or any combination of them. It did very well with my pressing and releasing all the various buttons on my control panel. I can slam and release all the buttons in any order and it works great and is fast. I played a bit of Asteroids Deluxe using it and as usual took a beating for my lack of skill! The KB16 played great.
It did not fare as well on the PS/2 passthrough keyboard slam and release tests. With the extra keyboard plugged in, it will pass simple keystrokes just fine. But, if you try to press and release a bunch of keys at the same time, you can lockup the KB16. Once locked up, the only way to get it working again is a power off and power on. At first I thought perhaps it was just my specific keyboard, but I tried two other keyboards and both were also capable of locking up the KB16 with slam and release keypressing. Tokn Media informed me that they have never done keyboard slam testing like I did, but that they have testing the KB16 cascaded with other KB16’s. I would have liked to test this, but without two KB16’s on hand, I was unable to.
The KB16 shines for one particular application: A simple arcade project requiring 16 inputs or less that won’t need the keys to change frequently. This could be something like a VAntAGE project, a dedicated single game cabinet or mini-cabinet, or a custom jukebox perhaps. The best feature of the KB16 is its support for NVRAM, no other encoder at this price point has NVRAM capability.
What is NVRAM? It is an acronym that stands for non-volatile random access memory, but what it really means is that the encoder will remember its configuration even when powered off. This is useful because you can configure the encoder the way you want it and it will stay that way. For encoders that don't have NVRAM capability, you must reprogram them each time you power them up unless you use whatever their default configuration is.
I don’t think the lockup issue with the keyboard passthrough is a huge problem because I wouldn’t recommend daisy chaining KB16’s for economical reasons. Instead of purchasing two KB16’s to chain together, it would be cheaper to buy an encoder with more inputs to begin with.
Here is a comparison chart with comparable encoders:
(Click to Open Larger Image in New Window)