"glen herrmannsfeldt" <[email protected]> wrote in message
news:h233ph$de8$[email protected]..
> It sounds like zeros are good and ones are bad.
>

That's been my experience too...it's due to the pointy-ness of the 1. Those
1s can nick some of the internals of the FPGA which can lead to internal
shorts between power and ground. If you have a bitstream with ~million or
so 1s in them you have a fairly good chance of running into this problem.
The 0s have no sharp edges and generally load just fine, the only problem
can be if some of them inadvertantly become Os which can get stuck in the
bitstream causing blockage and a bloating of the device which will then fail
to load.

KJ