Update for my work today:
I got the hash count working correctly now. I'm still finding a lot of instability with USB that I didn't see before. Random errors, write errors, disconnects that never happened when using serial mode. I haven't tried tracking that down as my attention has been on improving the result capture, which I think is still unreliable due to poor clock delay.
Someone requested scope traces before and I still haven't been able to get the scope USB save to work. It just errors out or write 0 byte files - useless. It says use FAT32, which I am, but still doesn't work with either 512MB or 16GB flash sticks. I'll probably have to get some support for that but in the mean time I used my camera to capture some screen shots.
These traces are with 1K pullups and 500 ohm pullups (no 470 on hand so doubled up the 1K) but not much difference shown. This is with 330pF capacitors now. I'm going to try adding a second NOR gate with RC between to try and get a better delay and more defined capture edges. It's not clear if the PIC has Schmitt inputs but the NOR gates do so this should give better definition. This would result in a small board change and part change from 1G02 to 2G02, only 5 cents in cost, but if it makes the result capture more reliable it's well worth it. Looking at the traces I'm a bit amazed it captures results at all. It does but I think it's the source of HW errors in cgminer as even one bit miscaptured would throw a nonce out. Whether it gets a 1 or 0 right now looks like a dice roll.
The whole wave
http://i.imgur.com/G208Dxd.jpgIn a bit closer
http://i.imgur.com/t7OMtZh.jpg500 ohm pullups, 330pF, 200nS/div
http://i.imgur.com/IfJcaMy.jpg1K pullups, 330pF, 100nS/div
http://i.imgur.com/Jfhd3cu.jpgI think you have problem with RC OWON probe compensation.
