You've got that right :P Well, several projects can be thought off in this scenario, but if you want to keep it mildly useful, try to do something with audio tubes connected to an '11 (OK, here's a spoiler: "you'll make a PDP11-driven music player using a tube-based audio backend"), or such. You could go into analog computing as well, but that can be kinda hairy. This more or less only requires building a usable D/A converter on the '11, which then interfaces to the tubes. I'd use a DMA- based 16-bit DA controller. Cheers, Fred (smiling @ his nano-11 system running Ultrix, all the size of a matchbox..)