Well, as some of you may remember this is something I did about two years ago... and then got out of college, got a job, other priorities, and more or less disappeared. I'm probably never going to have time to improve this, but it's been good enough that I've used it in my car of all that time without being annoyed enough to change it. So if other people are still interested in it, you might as well start where I left off...

Source, and docs on the various VFDs that I have: http://applesolutions.com/Empeg/remote/

Pictures of it getting into my car: http://gallery.applesolutions.com/v/vincent/hardware/Empeg/Trunk+Mount/

The software was written over, oh, maybe a weekend; There's lots of room for optimization in the drawing. The main ugly bit is that the Empeg writes out the boot log to the serial during boot; Since my display doesn't run at 115.2k, it comes out as garbled junk. It's mainly for the 3900 (specifically the 256x64D one), but it looks like I started working on a 7100 too because the command set is almost the same. The k610a is rather different, and the 800 that you're linking too looks different too, but you can just change the implementations of the drawing calls to send the right commands.

For input, I found a neat Grayhill joystick that has the 7 empeg actions (up/down/left/right, knob+/-/push) all on one knob. A Basic stamp and a couple transistors and gates convert it's output into serial character presses that are sent to another app running on the empeg. It gets unresponsive when the player is particularly busy, kinda lame. The rest of the board in the pictures is a switching 12->5vdc transformer to power everything.. the display is just connected straight to the empeg's serial line.

I'll be glad to help wherever I can if you have any questions.. I'll try to check the forum, but probably best to email me: [my first name] at godaddy dot com

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Vincent