tashtari
PIC Whisperer
As I mentioned earlier, the DCD protocol was designed with the capability to daisy chain together a theoretically-infinite number of DCDs, with Mac pulsing the PH3 line to advance to the next one. I at first didn't think that the PIC would be fast enough to respond to this, but I measured on the scope and apparently those pulses are pretty leisurely-paced, about 5 us wide and 24 us apart. What I do wonder, though, is whether one of the faster macs that supported the HD20 (Classic II, LC, IIsi, IIci, some others, maybe more with the ROMinator SIMM) would go too fast for the firmware to detect. I don't have the means to test this right now, I only have a 512ke and a Classic and they're both members of the 8 MHz club...