I bought a BTC-5100c for $30 bucks on eBay.
The layout is odd but surprisingly easy to get used to. Notice the tiny function row and tiny space bar. All keys are MX mount
except the function row (more of that below) which is really nice because a good many of the recent GMK sets will fit this board with the exception of the spacebar (and you'll have an off legend function and enter key).
Because I couldn't find this info anywhere, the odd shaped key caps are as follows:
| Key | Unit Size |
| Space | 4.5u |
| Fn, Ctrl, Alt | 1.5u |
| Backspace | 1.5u |
| Enter | 1.75u |
| R Shift | 1.25u |
| Func Row | 0.853u |
Note:
4.5 units (85mm wide, 3 mounts, 34.671mm apart)
One center mount and two stabiliser mounts 1.82 units (34.671mm) left and right of the center.
For this space bar exist molds in the Signature Plastics SA-family.
The spacebar on the BTC fits the description (including stab spacing) above but is not SA profile. Also, as of 8/25/16, Signature Plastics
does not currently sell a 4.5u spacebar on
www.pimpmykeyboard.com, only 4u and 4.75u. I'm not sure if the Deskthority Wiki is incorrect, or SP has stopped production, or if the mold still exists (if it ever did).
And here is the keyset in the keyboard layout editor (Colors not true to life, I just picked some).
BTC-5100c LayoutThe sound seems louder than my Topre Type Heaven but that has been silenced for most of its life so I don't quite remember the original sound. The BTC has less of a Topre "thock" and more of an "aquatic" sound. That's the best way to describe the sound although it's a **** description. I came across the video below a while back and based on the video alone, I knew I had to buy one. The video is a very accurate representation of the sound.
One thing to note is that the DIN model superior to the PS2 model. So if you're going to use it on USB you need: a DIN female to PS2 adapter (this is passive), and a PS2 to USB converter (this is active).
DIN model sounds better and I
think it feels better. Here's a video showing the difference in sound.
Finally, here's my tear down of the BTC-5100c.
Back of case. Flippers were scratchy, stiff and LOUD as **** but I put a drop of oil on each contact and it's silent now. Missing pad on the back but they're rock hard and not very grippy anyway. I plan on making some to replace them even though I use the flippers.
Caps off. I originally took the board apart to clean some of the grime out from under they keys and lube the sliders, though once I removed a few sliders, I realised they were already lubed which is pretty nice for a board of this age. I ended up having to re-lube anyway though because I washed the top shell of the case with dish soap. Weird stabs on the left shift. It's like a sleeve that some pegs on the key go into. Costar style stab on the spacebar (wire removed in this pic). MX stems on most keys. Function row is j
L to R: Left shift, alpha, function row keycaps. These caps are actually really decent. Thicker than SP DCS for sure. And though I don't have a photo, the legends are actually a decent bold laser etch -- not very fuzzy at all.
Back of case removed. Weird grounding cable to a metal layer (2 to 3 times thicker than tin foil). Controller looks pretty clean and tidy. It's cool that cord is detachable without splicing, although it's in the case so that doesn't do much good. I have plans for a teensy/usb conversion for full programmability and I want to use the original thick, coiled cord if possible.
Foil and cord removed. Unfortunately I could not find a build date anywhere
Nice domes, really nice PCB for the price of the keyboard. I didn't remove the domes because they were semi-stuck to the PCB and I didn't wanna damage it or potentially ruin the sound/feel. The left shift dome is an odd green. It's also weird that there are 2 unused contacts on either side of shift dome. Not sure what those were for as this is the only layout I've seen on this board.
This keyboard doesn't get much attention as of late and I think that's primarily because of the lack of information on it. I hope what I've provided here prompts people to go get their hands on a serious $30 Topre alternative with MX keycap compatibility.
Thanks for reading!
