From: anthonypaulo@gmail.com   
      
   So I've been fooling around with my fpga on a peripheral card doing reads and   
   writes to the bus, trying to get the timing just right, but it's such a pain   
   to power off the apple ii, remove the peripheral card, plug in the usb cord to   
   the fpga, flash the    
   new vhdl update, unplug usb cord, put the card back in the slot and power up   
   the apple II again, ad nauseum. To simplify things I decided to use an   
   external usb power with an on/off switch and plug the usb cord into that and   
   leave the cord plugged into    
   the fpga while it's in the apple ii slot. I have to make sure to have either   
   the usb port or the apple ii off when the other's on, or else there'll be a   
   lot of smoke.   
      
   As I finished flashing an update to the fpga card, I happened to glance at my   
   oscillosope which was connected to my fpga and I saw it generating a wave   
   form, a 1mhz signal that can only be generated if phase0 was actively feeding   
   it, but the apple II was    
   off! I was scratching my head... Surely the motherboard clock can't still be   
   working with the apple ii powered off, can it? So I unplugged the power cord   
   from the apple ii and... the waveform was still there! At that moment I   
   realized that the USB    
   powering the fpga was also feeding power to the apple ii via the 5v line, and   
   that must be powering the clock. It must also be powering the ROM (and maybe   
   RAM?) because I was able to read from it just fine.   
      
   I wanted to ask you guys out there in the know... is this okay or am I at risk   
   of damaging something? Assuming it's okay, can I rely on debugging it this way   
   with the apple ii power off, or will the timing be different with the apple II   
   on thus making    
   any debugging while off pointless?   
      
   Many thanks in advance.   
      
   Anthony   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)