Actually, the empeg has always worked at low voltages - we've tested it down to 8.5v(*) - but the powerfail interrupt kicked in (and still does) at 10.16v. Basically, when the empeg sees the voltage drop below this point, it decides that the power is failing and does things like blank the display and save where it is in the current tune (it does this fast enough so you can even yank it out of the dash it it remembers where it was).

In about beta5 Mike added a feature which, if the CPU was still running a couple of seconds after a powerfail, it would turn the display back on and carry on playing music. Problem was, we found a bug in the timer code here which caused the empeg to lock solid if a powerfail interrupt ocurred at a very particular point during bootup - the comparator is very sensitive and reacts even to small glitches of voltage below 10.16v, like the ones you get if the display powers up or the HDD has a current peak: the fix just cures this bug.

The next beta has some more speedups which have shaved about 1.5-2 seconds from the bootup time when on DC power (ie, in the car), and the empeg logo now comes up about 2 seconds after power on, so you know it's coming up!

Hugo
(*) Below 11v the sound quality suffers as the linear regulator which looks after the 4v outputs goes into oscillation. The digital side runs fine though.