Looks great!
After a few hours of hell I got my Digispark based MCU Interrupter working. It's good enough for a basic SSTC, and good enough for a basic level option to share with others, but I won't be fully endorsing it. The usb interfacing leaves a LOT to be desired. It isn't fully usb compliant, the connection is buggy as hell, and it is a nightmare to get a pc to recognize it. At least my code works fine.
The good news is that the ATTiny85 itself works exactly as expected, aside from the internal clock being about 20% slow. The main problem is just the digispark as a platform. It looks like I'm going to have to get an Arduino UNO/DUE when I can afford to and just make an ATTiny85 ISP Programmer Shield for future ATTiny projects. I'm glad I only spent $20 on the digispark + protoboard shield + breakout shield + shipping. I'm glad I did get those two shields as well, the proto one will be used for all the connections for my actual interrupter, and the breakout shield made it a LOT easier to do debugging and testing.
I think I'll use a full blown UNO/DUE for my 1MHz DRSSTC interrupter though. I can't afford to be blowing bridges because the internal clock on the ATTiny is 20% out.
It just sucks because at $8 for a $2MCU + $2VREG + built in dev board + basic breakout was an awesome deal. I guess the arduino based ISP saves money in the long run, but it is a lot harder pill to swallow.