OK, not my week.
Mega1284A not responding to ISP at all. AVRISPII, STK500, Studio 4.18 SP3.
No I haven't changed any of the fuses. Only power, SPI and two port pins connected to more than just tracks (all correctly). No shorts.
Internal oscillator running as a 1 MHz square wave on the xtal out pin, but it is only about 10mV.
I'm not used to running AVRS on the internal oscillator, is this very low level normal, or is it a clue that soomething internal is dragging the oscillator down?
I suspect I may have bricked this one, possibly by a static zap (that would be the third or fourth time in nearly 40 years playing with cmos).